U.S. patent application number 12/572840 was filed with the patent office on 2010-01-28 for method and device for storing domain name system records, method and device for parsing domain name.
This patent application is currently assigned to HUAWEI TECHNOLOGIES CO., LTD.. Invention is credited to Guoqiao Chen, Lei Wang, Jian Yang.
Application Number | 20100023611 12/572840 |
Document ID | / |
Family ID | 38938022 |
Filed Date | 2010-01-28 |
United States Patent
Application |
20100023611 |
Kind Code |
A1 |
Yang; Jian ; et al. |
January 28, 2010 |
METHOD AND DEVICE FOR STORING DOMAIN NAME SYSTEM RECORDS, METHOD
AND DEVICE FOR PARSING DOMAIN NAME
Abstract
A method, device, and terminal for storing domain name system
(DNS) records are provided. The method includes: locally storing
received DNS records needed to be stored; and if the size of all
the stored DNS records does not satisfy a preset storing threshold,
deleting a part of the stored DNS records to make the size of the
remaining DNS records after deletion satisfy the storing threshold.
A domain name parsing method, device, and server are provided. The
method includes: receiving a DNS query request, where the DNS query
request carries a domain name needed to be parsed and at least one
of a service identity (ID) and user information; selecting a
network address corresponding to the domain name according to the
service ID and/or the user information; and if the corresponding
network address is selected, returning the selected network address
as a query result of the DNS query request.
Inventors: |
Yang; Jian; (Shenzhen,
CN) ; Chen; Guoqiao; (Shenzhen, CN) ; Wang;
Lei; (Shenzhen, CN) |
Correspondence
Address: |
Huawei Technologies Co., Ltd.;c/o Darby & Darby P.C.
P.O. Box 770, Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
HUAWEI TECHNOLOGIES CO.,
LTD.
Shenzhen
CN
|
Family ID: |
38938022 |
Appl. No.: |
12/572840 |
Filed: |
October 2, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/CN2008/070604 |
Mar 27, 2008 |
|
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12572840 |
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Current U.S.
Class: |
709/223 ;
707/E17.014; 709/245 |
Current CPC
Class: |
H04L 69/28 20130101;
H04L 61/1511 20130101; H04L 29/12066 20130101; H04L 61/1552
20130101; H04L 29/12132 20130101 |
Class at
Publication: |
709/223 ;
709/245; 707/3; 707/E17.014 |
International
Class: |
G06F 15/173 20060101
G06F015/173; G06F 15/16 20060101 G06F015/16; G06F 17/30 20060101
G06F017/30 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 4, 2007 |
CN |
200710100503.6 |
Claims
1. A method for storing domain name system (DNS) records,
comprising: locally storing received DNS records needed to be
stored; and if the size of all the stored DNS records does not
satisfy a preset storing threshold, deleting a part of the stored
DNS records to enable the size of the remaining DNS records after
deletion to satisfy the storing threshold.
2. The method for storing DNS records according to claim 1, wherein
the locally storing the received DNS records needed to be stored
comprises: locally storing newly received DNS records.
3. The method for storing DNS records according to claim 1, wherein
the locally storing the received DNS records needed to be stored
comprises: locally storing newly received DNS records whose
time-to-live (TTL) is not 0.
4. The method for storing DNS records according to claim 1,
wherein: the circumstance that the size of all the stored DNS
records does not satisfy a preset storing threshold comprises: the
size of all the stored DNS records is greater than the preset
storing threshold; and the circumstance that the size of the
remaining DNS records after deletion satisfies the storing
threshold comprises: the size of the remaining DNS records after
deletion is not greater than the storing threshold.
5. The method for storing DNS records according to claim 1,
wherein: the circumstance that the size of all the stored DNS
records does not satisfy a preset storing threshold comprises: the
size of all the stored DNS records is not smaller than the preset
storing threshold; and the circumstance that the size of the
remaining DNS records after deletion satisfies the storing
threshold comprises: the size of the remaining DNS records after
deletion is smaller than the storing threshold.
6. The method for storing DNS records according to claim 1, wherein
the deleting a part of the stored DNS records to make the size of
the remaining DNS records after deletion satisfy the storing
threshold comprises: if expired DNS records exist, deleting the
expired DNS records; and if the size of the remaining DNS records
still does not satisfy the storing threshold after deleting the
expired DNS records, deleting a part of the DNS records once again
to make the size of the remaining DNS records after deletion
satisfy the storing threshold.
7. The method for storing DNS records according to claim 6, wherein
the deleting a part of the DNS records once again comprises at
least one of these processes: deleting a part of the DNS records
closest to expiration; selecting and deleting a part of the DNS
records from all the DNS records about multiple IP addresses
corresponding to one domain name; deleting the DNS records in
sequence following a storing order; and deleting a part of the DNS
records of low use rate.
8. The method for storing DNS records according to claim 1, wherein
the deleting a part of the stored DNS records to enable the size of
the remaining DNS records after deletion to satisfy the storing
threshold comprises: if expired DNS records do not exist, deleting
a part of the DNS records to enable the size of the remaining DNS
records after deletion to satisfy the storing threshold.
9. The method for storing DNS records according to claim 1, wherein
before the locally storing the received DNS records needed to be
stored, the method further comprises: sending a DNS query request
to a DNS server, wherein the DNS query request carries at least one
of a service identity (ID) and user information; and receiving at
least one DNS record returned by the DNS server according to the
DNS query request.
10. A device for storing domain name system (DNS) records,
comprising: a storage unit, adapted to store received DNS records
needed to be stored; a DNS record size detection unit, adapted to
detect whether the size of all the DNS records stored in the
storage unit satisfies a preset storing threshold; and a DNS record
cleanup unit, adapted to delete a part of the DNS records stored in
the storage unit if the size of all the stored DNS records does not
satisfy the storing threshold, so as to enable the size of the
remaining DNS records after deletion to satisfy the storing
threshold.
11. The device according to claim 10, wherein: the DNS record size
detection unit is specifically adapted to compare the size of all
the DNS records stored in the storage unit with the preset storing
threshold; and the DNS record cleanup unit is specifically adapted
to delete a part of the DNS records stored in the storage unit when
the size of all the stored DNS records is greater than the storing
threshold, so that the size of the remaining DNS records after
deletion is not greater than the storing threshold.
12. The device according to claim 10, wherein: the DNS record size
detection unit is specifically adapted to compare the size of all
the DNS records stored in the storage unit with the preset storing
threshold; and the DNS record cleanup unit is specifically adapted
to delete a part of the DNS records stored in the storage unit when
the size of all the stored DNS records is not smaller than the
storing threshold, so that the size of the remaining DNS records
after deletion is smaller than the storing threshold.
13. The device according to claim 10, wherein the device for
storing domain name system (DNS) records is a terminal.
14. A domain name parsing method, comprising: receiving a domain
name system (DNS) query request, wherein the DNS query request
carries a domain name needed to be parsed and at least one of a
service identity (ID) for identifying a service type and user
information for identifying a user ID; selecting a network address
corresponding to the domain name according to at least one of the
service ID and the user information; and if the corresponding
network address is selected, returning the selected network address
as a query result of the DNS query request.
15. The domain name parsing method according to claim 14, wherein
when the DNS query request carries the service ID, the selecting
the network address corresponding to the domain name according to
the service ID comprises: selecting a network address of a network
equipment corresponding to the domain name and capable of providing
the service.
16. The domain name parsing method according to claim 14, wherein
when the DNS query request carries the user information, the
selecting the network address corresponding to the domain name
according to the user information comprises: selecting a network
address of a network equipment corresponding to the domain name and
which allows a user to access.
17. The domain name parsing method according to claim 14, wherein
authentication data for security authentication is returned when
the selected network address is returned as the query result of the
DNS query request.
18. The domain name parsing method according to claim 14, wherein
if no network address corresponding to the domain name is selected
according to at least one of the service ID and the user
information, the method further comprises: providing an address of
at least one other DNS server to a terminal that sends the DNS
query request; and sending, by the terminal, the DNS query request
to the other DNS servers, wherein the DNS query request carries at
least one of the service ID and the user information, until one of
the DNS servers provides a network address of a network equipment
that conforms to at least one of the service ID and the user
information.
19. The domain name parsing method according to claim 14, wherein
if no network address corresponding to the domain name is selected
according to at least one of the service ID and the user
information, the method further comprises: forwarding the DNS query
request to other DNS servers, until one of the DNS servers provides
a network address of a network equipment that conforms to at least
one of the service ID and the user information.
20. A domain name parsing device, comprising: a domain name system
(DNS) query request receiving unit, adapted to receive a DNS query
request, wherein the DNS query request carries a domain name needed
to be parsed and at least one of a service identity (ID) for
identifying a service type and user information for identifying a
user ID; a network address selecting unit, adapted to select a
network address corresponding to the domain name according to at
least one of the DNS service ID and the user information; and a
network address providing unit, adapted to return the selected
network address as a query result of the DNS query request when the
corresponding network address is selected.
21. The domain name parsing device according to claim 20, wherein
the domain name parsing device is a DNS server.
22. A domain name parsing result acquisition method, comprising:
sending a domain name system (DNS) query request to a DNS server,
wherein the DNS query request carries a domain name needed to be
parsed and at least one of a service identity (ID) for identifying
a service type and user information for identifying a user ID; and
receiving at least one network address corresponding to the domain
name provided by the DNS server, wherein the network address is
selected by the DNS server according to at least one of the service
ID and the user information.
23. A domain name parsing result acquisition device, comprising: a
domain name system (DNS) query request sending unit, adapted to
send a DNS query request to a DNS server, wherein the DNS query
request carries a domain name needed to be parsed and at least one
of a service identity (ID) for identifying a service type and user
information for identifying a user ID; and an IP address receiving
unit, adapted to receive at least one network address corresponding
to the domain name provided by the DNS server, wherein the network
address is selected by the DNS server according to at least one of
the service ID and the user information.
24. The domain name parsing result acquisition device according to
claim 23, further comprising: an information loading unit, adapted
to load at least one of the service ID for identifying the service
type and the user information for identifying the user ID into the
DNS query request.
25. The domain name parsing result acquisition device according to
claim 23, wherein the domain name parsing result acquisition device
is a terminal.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of International
Patent Application No. PCT/CN2008/070604, filed on Mar. 27, 2008,
which claims priority to Chinese Patent Application No.
200710100503.6, filed on Apr. 4, 2007, both of which are hereby
incorporated by reference in their entireties.
FIELD OF THE DISCLOSURE
[0002] The present invention relates to a domain name system (DNS)
technique, more particularly to a technique for storing DNS records
and a technique for parsing domain name.
BACKGROUND OF THE DISCLOSURE
[0003] In the current Internet Protocol (IP) network, one domain
name is corresponding to at least one IP address, and the
corresponding relation between the domain name and the IP addresses
can be stored in a domain name system (DNS) server. When a terminal
intends to get access to a network equipment corresponding to a
certain domain name, the terminal queries the DNS server about IP
addresses corresponding to the domain name, thereby communicating
or implementing other operations with the corresponding network
equipment according to the IP addresses. In practical applications,
the terminal may access the network equipment corresponding to the
same domain name many times, so the terminal needs to frequently
query the DNS server about the corresponding relation between the
domain name and the IP addresses.
[0004] Additionally, when a terminal intends to get access to a
network equipment corresponding to a certain domain name, the
terminal usually sends a query request which carries the domain
name to the DNS server, and the DNS server returns an IP address
corresponding to the domain name as a response message to the
terminal. In practical applications, one domain name may be
corresponding to multiple IP addresses. The network equipment
corresponding to each IP address may provide the same service, and
definitely may provide different services respectively. Therefore,
it is possible that the IP address returned by the DNS server to
the terminal is inappropriate, which probably results in that the
terminal sends a query request to the DNS server once again to
acquire the appropriate IP address, thus increasing unnecessary
network traffics.
SUMMARY OF THE INVENTION
[0005] Accordingly, the present invention is directed to a method
and device for storing domain name system (DNS) records, which are
capable of reducing the burden of a terminal with a small storage
capacity when frequently querying the DNS about a domain name.
[0006] The present invention is also directed to a domain name
parsing method and device, which are capable of completing a domain
name parsing process in consideration of a DNS query request
sender.
[0007] In an embodiment of the present invention, a method for
storing DNS records is provided. The method includes:
[0008] locally storing received DNS records needed to be stored;
and
[0009] if the size of all the stored DNS records does not satisfy a
preset storing threshold, deleting a part of the stored DNS records
to enable the size of the remaining DNS records after deletion to
satisfy the storing threshold.
[0010] In an embodiment of the present invention, a device for
storing DNS records is provided. The device includes:
[0011] a storage unit, adapted to store received DNS records needed
to be stored;
[0012] a DNS record size detection unit, adapted to detect whether
the size of all the DNS records stored in the storage unit
satisfies a preset storing threshold; and
[0013] a DNS record cleanup unit, adapted to delete a part of the
DNS records stored in the storage unit if the size of all the
stored DNS records does not satisfy the storing threshold, so as to
enable the size of the remaining DNS records after deletion to
satisfy the storing threshold.
[0014] In an embodiment of the present invention, a terminal is
provided. The terminal includes:
[0015] a storage unit, adapted to store received DNS records needed
to be stored;
[0016] a DNS record size detection unit, adapted to detect whether
the size of all the DNS records stored in the storage unit
satisfies a preset storing threshold; and
[0017] a DNS record cleanup unit, adapted to delete a part of the
DNS records stored in the storage unit if the size of all the
stored DNS records does not satisfy the storing threshold, so as to
enable the size of the remaining DNS records after deletion to
satisfy the storing threshold.
[0018] In an embodiment of the present invention, a method for
parsing a domain name is provided. The method includes:
[0019] receiving a DNS query request, where the DNS query request
carries a domain name needed to be parsed and at least one of a
service identity (ID) for identifying a service type and user
information for identifying a user ID;
[0020] selecting a network address corresponding to the domain name
according to at least one of the service ID and the user
information; and
[0021] if the corresponding network address is selected, returning
the selected network address as a query result of the DNS query
request.
[0022] In an embodiment of the present invention, a device for
parsing a domain name is provided. The device includes:
[0023] a DNS query request receiving unit, adapted to receive a DNS
query request, where the DNS query request carries a domain name
needed to be parsed and at least one of a service ID for
identifying a service type and user information for identifying a
user ID;
[0024] a network address selecting unit, adapted to select a
network address corresponding to the domain name according to at
least one of the DNS service ID and the user information; and
[0025] a network address providing unit, adapted to return the
selected network address as a query result of the DNS query request
when the corresponding network address is selected.
[0026] In an embodiment of the present invention, a DNS server is
provided. The DNS server includes:
[0027] a DNS query request receiving unit, adapted to receive a DNS
query request, where the DNS query request carries a domain name
needed to be parsed and at least one of a service ID for
identifying a service type and user information for identifying a
user ID;
[0028] a network address selecting unit, adapted to select a
network address corresponding to the domain name according to at
least one of the DNS service ID and the user information; and
[0029] a network address providing unit, adapted to return the
selected network address as a query result of the DNS query request
when the corresponding network address is selected.
[0030] In an embodiment of the present invention, a method for
acquiring a domain name parsing result is provided. The method
includes:
[0031] sending a DNS query request to a DNS server, where the DNS
query request carries a domain name needed to be parsed and at
least one of a service ID for identifying a service type and user
information for identifying a user ID; and
[0032] receiving at least one network address corresponding to the
domain name provided by the DNS server, where the network address
is selected by the DNS server according to at least one of the
service ID and the user information.
[0033] In an embodiment of the present invention, a device for
acquiring a domain name parsing result is provided. The device
includes:
[0034] a DNS query request sending unit, adapted to send a DNS
query request to a DNS server, where the DNS query request carries
a domain name needed to be parsed and at least one of a service ID
for identifying a service type and user information for identifying
a user ID; and
[0035] an IP address receiving unit, adapted to receive at least
one network address corresponding to the domain name provided by
the DNS server, where the network address is selected by the DNS
server according to at least one of the service ID and the user
information.
[0036] In an embodiment of the present invention, a terminal is
provided. The terminal includes:
[0037] a DNS query request sending unit, adapted to send a DNS
query request to a DNS server, where the DNS query request carries
a domain name needed to be parsed and at least one of a service ID
for identifying a service type and user information for identifying
a user ID; and
[0038] an IP address receiving unit, adapted to receive at least
one network address corresponding to the domain name provided by
the DNS server, where the network address is selected by the DNS
server according to at least one of the service ID and the user
information.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a schematic view of the structure of an Internet
domain name according to an embodiment of the present
invention;
[0040] FIGS. 2A-2B are a flow chart of a method for storing DNS
records according to an embodiment of the present invention;
[0041] FIG. 3 is a flow chart of a method for parsing a domain name
according to an embodiment of the present invention;
[0042] FIG. 4 is a flow chart of another method for parsing a
domain name according to an embodiment of the present invention;
and
[0043] FIG. 5 is a schematic view of an embodiment of iterative
parsing.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0044] All the embodiments of the present invention relate to the
DNS technique. The related content of the DNS is first introduced
before a detailed description of the embodiments of the present
invention.
[0045] Hosts on the Internet can be identified by many means, for
example, through their hostnames. As the hostname is mnemonic, for
example, cnn.com and www.yahoo.com, people are more willing to use
a hostname to identify a host. However, the hostname does not
provide much information about the location of the host in the
Internet. For example, if the hostname of a certain host is
sina.com.cn, it is determined that the host is located in China,
but no further location information is provided. Additionally, the
hostname is composed of letters, numbers, and symbols with variable
length, so it is difficult for the router to process.
[0046] In view of the above deficiency in identifying a hostname,
hosts on the Internet may also be identified by IP addresses.
Transmission Control Protocol (TCP)/Internet Protocol (IP)
communication among the hosts on the Internet is accomplished
through the IP addresses, and each host on the Internet has one IP
address as its unique identification. The IP address is
hierarchical. If an address is scanned from left to right, the
location information about the corresponding host on the Internet
can be obtained more explicitly.
[0047] However, the IP address is a numerical name that is hard to
remember or understand. As a result, a problem arises, i.e., one
host can be identified by a hostname or by an IP address. In
practical applications, people are more willing to use the hostname
to identify the host since the hostname is easy to remember; while
routers and other network equipments prefer fixed-length and
hierarchically structured IP addresses. For the convenience of
application, the TCP/IP provides a symbol naming mechanism for the
host, i.e., the domain name system (DNS). The DNS is a distributed
database implemented in a hierarchy of name servers, and also an
application-layer protocol that allows client hosts and name
servers to communicate in order to provide the domain name
translation service. The name server is usually a UNIX host that
runs the Berkeley Internet Name Domain (BIND, a software name)
software. The DNS protocol runs over the User Datagram Protocol
(UDP), and its port number is 53. The DNS is capable of mapping
dull and meaningless numbers into words or abbreviations of words
with specific meanings that are easy to remember and understand.
Particularly, during the construction of a website, the DNS is a
primary issue that needs to be settled, which is also the basis for
realizing www, File Transfer Protocol (FTP), E-mail, and other
Internet applications.
[0048] Other application-layer protocols, such as Hypertext
Transfer Protocol (HTTP), Simple Mail Transfer Protocol (SMTP), and
FTP, generally adopt the DNS to translate a hostname provided by
the user into an IP address. For example, when a user employs a
browser (i.e., an HTTP client) running on the local host to request
http://www.yesky.com, in order to send an HTTP request message to
the web server named www.yesky.com, the browser must obtain the IP
address of the web server. The browser extracts the hostname from
the Uniform Resource Locator (URL), and transfers the extracted
hostname to the DNS application client on the local host. The DNS
application client sends a DNS query request message containing the
extracted hostname to a DNS server, and then receives a reply
message containing the IP address corresponding to the extracted
hostname. After that, the browser opens a TCP connection to the
HTTP server located at the extracted IP address. In addition to the
translation service from the hostname to the IP address, the DNS
also provides other important services as follows.
[0049] 1. Hody aliasing: a host with a complicated hostname may
have one or more alias names. For example, a hostname
relay1.west-coast.enterprise.com may have other two aliases,
respectively, enterprise.com and www.enterprise.com. Herein, the
hostname relay1.west-coast.enterprise.com is called a canonical
hostname, and the other two are called alias hostnames. Compared
with the canonical hostname, the alias hostname is easier to
remember. The DNS application client can invoke the DNS to obtain
the canonical hostname and the IP address corresponding to a given
alias hostname.
[0050] 2. Mail server aliasing: an e-mail address generally needs
to be easy to remember. For example, Bob (a user) has a hotmail
account, and his e-mail address may simply be Bob@hotmail.com.
However, the hostname of the hotmail server is more complicated
than hotmail.com and is hard to remember. The e-mail application
can invoke the DNS to obtain the canonical hostname and the IP
address corresponding to a given alias hostname. In practical
applications, the DNS allows the web server and mail server of one
company to use the same alias hostname. For example, the web server
and the mail server of a company may be both named as
enterprise.com.
[0051] 3. Load distribution: the DNS is increasingly adapted to
perform load distribution among multiple replicated servers, such
as replicated web servers. For example, busy sites, like cnn.com,
are usually replicated over multiple web servers, and each web
server runs on a different end system and has a different IP
address. As for the replicated web servers, a single canonical
hostname is associated with a set of IP addresses, and the set of
IP addresses are stored in the DNS server. When a terminal sends a
DNS query request for a hostname mapped to a set of IP addresses,
the DNS server responds with the entire set of IP addresses, but
rotates the ordering of the addresses within each reply. When
getting access to a website, the browser generally sends an HTTP
request message to the IP address arranged the first in the set
that is queried by the DNS client. The DNS rotates to distribute
the traffic of the website among all the replicated web servers.
The e-mail application may also adopt the DNS rotation, so that
multiple mail servers can have the same alias name.
[0052] The naming structure of the DNS is called a domain name
space. The domain name space is a tree-like and hierarchically
structured distributed database. A domain is a sub-tree or a branch
of the domain name space, and the root node of the tree is a root
domain, which is not named and denoted by ".". The node that is
closest to the root domain in the tree is called a top-level
domain. Each top-level domain is subdivided into multiple levels of
domains and multiple sub-domains, and the hosts are located at the
leaf nodes of the tree. A complete domain name is composed of node
identifiers in the path from a node to the root node of the tree in
an ordered sequence, where the node identifiers are separated by
".".
[0053] FIG. 1 shows a domain constituted by a sub-tree with ibm as
its root and having a domain name of ibm.com. The www server,
assigned with a domain hostname, is a host under the domain
nankai.edu.cn, and has a complete domain name of www.nankai.edu.cn.
A set of formal universal standard labels has been specified in the
Internet, and internationalized top-level domain names are formed,
for example, com for commercial organizations, and edu for
educational institutions. Each country applying for joining the
Internet is regarded as a top-level domain, and registers for a
top-level domain name at the Internet Corporation for Assigned
Names and Numbers (ICANN). The domain name of a country is
identified by the country code, e.g., cn for China, and jp for
Japan.
[0054] Only some basic contents about the DNS technique are
described above, and the embodiments of the present invention will
be described in detail below.
[0055] In practical applications, if a terminal intends to get
access to a network equipment, the terminal usually sends a DNS
query request to the DNS server, requesting the DNS server to parse
a domain name (also referred to as a hostname) carried by the DNS
query request. After parsing the domain name, the DNS server
returns a parsing result to the terminal. The parsing result may be
an IP address corresponding to the domain name or other related
information, and the parsing result is called DNS records herein.
After receiving the DNS records, the terminal stores the DNS
records, so that when getting access to the same network equipment
subsequently, the terminal does not need to query the DNS server
about the IP address corresponding to the domain name again, but
directly accesses the network equipment according to the IP address
in the stored DNS records.
[0056] Hereinafter, a technical solution of a method for storing
DNS records according to an embodiment is illustrated. The method
includes: locally storing newly received DNS records at a terminal;
and if the size of all the stored DNS records is greater than or
equal to a preset storing threshold, deleting a part of the stored
DNS records, so that the size of the remaining DNS records is not
greater than or is smaller than the storing threshold. It should be
noted that, the size of all the stored DNS records may be
determined in two manners and two types of corresponding results
are obtained. That is, if the size of all the stored DNS records is
greater than the preset storing threshold, a part of the DNS
records is deleted, so that the size of the remaining DNS records
is not greater than the storing threshold; and if the size of all
the stored DNS records is equal to the preset storing threshold, a
part of the DNS records is deleted, so that the size of the
remaining DNS records is smaller than the storing threshold.
[0057] In the above embodiment of the method, a part of the stored
DNS records is deleted in the following manner: if expired DNS
records exist, deleting the expired DNS records; and if the size of
the remaining DNS records is still greater than or equal to the
storing threshold, deleting a part of the DNS records once again,
so that the size of the remaining DNS records is not greater than
or is smaller than the storing threshold.
[0058] In the above embodiment of the method, a part of the DNS
records may be deleted once again in at least one of the following
manners: deleting a part of the DNS records closest to expiration;
selecting and deleting a part of the DNS records from all the DNS
records about multiple IP addresses corresponding to one domain
name; deleting the DNS records in sequence of storage; and deleting
a part of the DNS records of low use rate.
[0059] The use rate of the DNS records may be determined in various
manners. For example, each time the DNS records are used, the DNS
records are tagged once. When making statistics on or querying the
use rate of the DNS records, it is required to make statistic on
the number of the tags of the DNS records only.
[0060] In the above embodiment of the method, if expired DNS
records do not exist, a part of the DNS records is deleted, so that
the size of the remaining DNS records is not greater than or is
smaller than the storing threshold.
[0061] In the above embodiment of the method, before locally
storing the newly received DNS records at the terminal, a
time-to-live (TTL) in the new DNS records is determined, and if the
TTL is 0, the new DNS records are not locally stored at the
terminal; otherwise, the new DNS records are locally stored at the
terminal.
[0062] In the above embodiment of the method, before receiving the
new DNS records, the method further includes: sending a DNS query
request to the DNS server; and returning, by the DNS server, at
least one new DNS record according to the DNS query request. The
DNS query request may carry at least one of a service ID and user
information. In addition, the DNS server selects and returns at
least one IP address according to at least one of the service ID
and the user information.
[0063] With reference to FIGS. 2A-2B, an embodiment of a method for
storing DNS records is described in detail. Referring to FIGS.
2A-2B, the method includes the following steps.
[0064] In Step S201, a terminal receives new DNS records.
[0065] Herein, the terminal may take various forms, for example, a
personal computer (PC) or mobile phone. As for terminals with a
small storage capacity, such as mobile phones, the application of
the embodiment of the method may achieve better effects.
[0066] The DNS records are provided by a DNS server to the terminal
in the form of a response message. The response message carries at
least one resource record (RR). Each RR is a four-tuple that
contains the following fields: Name, Value, Type, and TTL. TTL
stands for the time for storing the RR or the time-to-live of the
IP address corresponding to the domain name. This time may be
determined by the DNS server, and definitely may be determined by
other network entities and the DNS server just forwards this time
to the terminal.
[0067] The meaning of Name and Value depends on Type.
[0068] If Type=A, Name is a hostname and Value is an IP address
corresponding to the hostname. Thereby, a Type A record provides
the mapping of a standard hostname to an IP address. For example,
(relay1.barfoo.com, 145.37.93.126, A) is a Type A record.
[0069] If Type=NS, Name is a domain, such as foo.com, and Value is
the hostname of an authoritative name server that can acquire the
IP address of the host in the domain. This record is adapted to
route the DNS query along the chain-link structure of the query.
For example, (foo.com, dns.foo.com, NS) is a Type NS record.
[0070] If Type=CNAME, Value is a canonical hostname corresponding
to the host alias NAME. This record provides a canonical hostname
corresponding to the hostname to the host that sends the query. For
example, (foo.com, relay1.barfoo.com, CNAME) is a Type CNAME
record.
[0071] If Type=MX, Value is a hostname of a mail server having the
host alias NAME. For example, (foo.com, mail.barfoo.com, MX) is a
Type MX record. The Type MX record enables the hostname of the mail
server to have simple alias.
[0072] For example, three DNS records are listed as follows:
[0073] www.sina.com.cn 202.20.132.102 2007-01-05 12:00
[0074] www.sina.com.cn 202.20.132.101 2007-01-05 12:00
[0075] www.sohu.com 202.20.131.101 2007-02-06 12:00
[0076] As for www.sina.com.cn, it is corresponding to two IP
addresses and indicates the TTL of the two IP addresses. As for
www.sohu.com, it is corresponding to one IP address and indicates
the TTL thereof.
[0077] In Step S202, it is determined whether the TTL in the DNS
record is 0 or not, and if the TTL in the DNS record is 0, the
process proceeds to Step S203; otherwise, the process proceeds to
Step S204.
[0078] Generally speaking, if TTL is 0, it indicates that this
record does not need to be stored; otherwise, it indicates that
this record is locally stored.
[0079] In Step S203, the DNS record is not stored or other
operations are performed, and then this process ends. The method
for not storing the DNS record may be discarding the DNS
record.
[0080] In Step S204, the DNS record is locally stored, and the
process proceeds to Step S205.
[0081] In Step S205, it is determined whether the size of all the
currently stored DNS records is not smaller than a preset storing
threshold, and if the size of all the currently stored DNS records
is not smaller than a preset storing threshold, the process
proceeds to Step S206; otherwise, the process ends.
[0082] Herein, the storing threshold is a standard set for a
storage space where the DNS records are stored, and the standard
may be set in many ways. For example, the standard may be set by
randomly dividing a storage space in a storage medium of the
terminal, or by estimating the amount of the DNS records to be
acquired and then dividing a storage space. After the storage space
is divided, it only needs to ensure that the set storing threshold
is not higher than or is completely lower than the capacity limit
of the storage space.
[0083] In Step S206, it is determined whether expired DNS records
exist or not, and if expired DNS records exist, the process
proceeds to Step S207; otherwise, the process proceeds to Step
S209. The expired DNS records refer to those with the TTL being 0
that indicates the expiration of the records.
[0084] In Step S207, the expired DNS records are deleted, and the
process proceeds to Step S208.
[0085] In Step S208, it is determined whether the size of the
remaining DNS records is still not smaller than the preset storing
threshold, and if the size of the remaining DNS records is still
not smaller than the preset storing threshold, the process proceeds
to Step S209; otherwise, the process ends. The remaining DNS
records herein refer to the DNS records that are not expired.
[0086] In Step S209, a part of the DNS records is deleted, and
proceed to Step S208.
[0087] A part of the DNS records may be deleted in various manners.
For example, the DNS records are deleted depending on the time
sequence of the DNS records to be expired; one or more DNS records
about multiple IP addresses corresponding to one domain name are
deleted; the DNS records are deleted in the sequence of storage; or
the less frequently used DNS records are deleted. It should be
noted that, the part of the DNS records herein may be one DNS
record or multiple DNS records.
[0088] The above embodiment of the method is only one embodiment of
storing the DNS records, and in fact variations can be made to this
embodiment to produce multiple embodiments. For example, in at
least one of steps S205 and S208, if it is determined that the size
of the currently stored DNS records is not smaller than the storing
threshold, it is further determined how much the size of the
currently stored DNS records exceeds the storing threshold, i.e.,
the difference value. Once the difference value is determined, in
at least one of the subsequent Step S207 and S209, a part of the
DNS records having a size equivalent to the difference value is
deleted. In practical applications, as new DNS records may be
stored subsequently, it is proper to delete the DNS records with a
size greater than the difference value.
[0089] The above embodiment of the method can be accomplished by a
device, and thus the embodiment of the present invention further
provides a device for storing DNS records. The device includes: a
storage unit, adapted to store newly received DNS records, and
store all the received DNS records needed to be stored; a DNS
record size detection unit, adapted to compare the size of all the
DNS records stored in the storage unit with a preset storing
threshold; and a DNS record cleanup unit, adapted to delete a part
of the DNS records stored in the storage unit if the DNS record
size detection unit detects that the size of all the DNS records
stored in the storage unit is greater than or equal to the preset
storing threshold, so that the size of the remaining DNS records is
not greater than or is smaller than the storing threshold.
[0090] The DNS records can be locally stored at a terminal, and
thus the embodiment of the present invention further provides a
terminal. The terminal includes: a storage unit, adapted to store
newly received DNS records, and store all the received DNS records
needed to be stored; a DNS record size detection unit, adapted to
compare the size of all the DNS records stored in the storage unit
with a preset storing threshold; and a DNS record cleanup unit,
adapted to delete a part of the DNS records stored in the storage
unit if the DNS record size detection unit detects that the size of
all the DNS records stored in the storage unit is greater than or
equal to the preset storing threshold, so that the size of the
remaining DNS records is not greater than or is smaller than the
storing threshold.
[0091] In all the embodiments of storing the DNS records according
to the present invention, if it is determined that the size of all
the stored DNS records is greater than or equal to the preset
storing threshold, a part of the DNS records is deleted, so that
the size of the remaining DNS records is not greater than or is
smaller than the storing threshold. In this manner, the problem
that the excessive storage of the DNS records may influence the
storage of other data is solved for terminals with a small storage
capacity.
[0092] In all the embodiments of storing the DNS records according
to the present invention, if it is determined that the size of all
the stored DNS records is greater than or equal to the preset
storing threshold, the expired DNS records are deleted. In this
manner, as these records are probably expired, the deletion of
these records may not produce negative influence on the subsequent
DNS query.
[0093] In all the embodiments of storing the DNS records according
to the present invention, after deleting the expired DNS records,
if the remaining DNS records are still greater than or equal to the
preset storing threshold, a part of the DNS records is selected and
deleted according to some strategies, where each strategy has its
own advantages. For example, the deletion of a part of data closest
to expiration may reduce the negative influence on the subsequent
DNS query. A part of the DNS records is selected and deleted from
all the DNS records about multiple IP addresses corresponding to
one domain name. As the multiple IP addresses corresponding to one
domain name may provide the same service, even if a part of the
records is selected and deleted, the corresponding IP address may
still be found when parsing the same domain name. The DNS records
are deleted according to their storage sequence, which is a
relatively simple management method, and a data structure like
queue can be adopted in storing the DNS records. A part of the DNS
records of low use rate is deleted, and since the DNS records of
low use rate have little impact on the subsequent DNS query, even
if these records are deleted, no negative influence will be
produced on the subsequent DNS query.
[0094] In practical applications, one domain name may be
corresponding to multiple IP addresses. The network equipment
corresponding to each IP address may provide the same type of
service, and definitely may provide different types of services.
When a terminal sends a DNS query request to the DNS server, if the
DNS server finds that the domain name carried by the query request
is corresponding to multiple IP addresses, it attempts to select an
appropriate IP address and return the IP address to the
terminal.
[0095] Hereinafter, a technical solution of a domain name parsing
method according to an embodiment is illustrated. This method
includes: receiving a DNS query request sent by a terminal, where
the DNS query request carries at least one of a service ID for
identifying a service type and user information for identifying a
user ID; selecting at least one IP address for the terminal
according to at least one of the service ID and the user
information; and returning the selected IP address to the
terminal.
[0096] In the above embodiment of the method, when the DNS query
request carries the service ID, at least one IP address
corresponding to a network equipment capable of providing such
service is selected and returned to the terminal.
[0097] In the above embodiment of the method, when the DNS query
request carries the user information, at least one IP address
corresponding to a network equipment that allows the terminal to
access is selected and returned to the terminal.
[0098] The DNS query request may exist as a DNS query request
message Question, and at least one of the service ID and the user
information are carried in the head part of the Question or in the
body part of the Question. Definitely, the DNS query request may
exist as a single message different from the DNS query request
message Question, and at least one of the service ID and the user
information are carried in the single message.
[0099] In the above embodiment of the method, when the selected IP
address is returned to the terminal, authentication data for
security authentication may also be provided to the terminal.
Thereby, the terminal may perform authentication on the
authentication data.
[0100] In the above embodiment of the method, if the at least one
IP address cannot be selected for the terminal according to at
least one of the service ID and the user information, the method
further includes: providing an address of at least one other DNS
server to the terminal, and sending, by the terminal, the DNS query
request to the other DNS servers, where the DNS query request
carries at least one of the service ID and the user information,
until one of the DNS servers provides an IP address of a network
equipment that conforms to at least one of the service ID and the
user information.
[0101] In the above embodiment of the method, if the at least one
IP address cannot be selected for the terminal according to at
least one of the service ID and the user information, the method
further includes: forwarding the DNS query request to other DNS
servers, until one of the DNS servers provides an IP address of a
network equipment that conforms to at least one of the service ID
and the user information.
[0102] In the above embodiment of the method, if the at least one
IP address cannot be selected for the terminal according to at
least one of the service ID and the user information, or no DNS
server can provide an IP address of a network equipment that
conforms to at least one of the service ID and the user
information, the information of parse error is returned to the
terminal.
[0103] With reference to FIG. 3, an embodiment of a domain name
parsing method is described in detail. Referring to FIG. 3, the
method includes the following steps.
[0104] In Step S301, a terminal sends a DNS query request to a DNS
server, where the DNS query request carries at least one of a
service ID and user information.
[0105] Herein, the terminal may take various forms, for example, a
PC or mobile phone.
[0106] The DNS query request may exist as a DNS query request
message Question, and at least one of the service ID and the user
information are carried in the head part of the Question message as
listed in Table 1, or carried in the body part of the Question
message as listed in Table 2, as Service TYPE and User
Authentication Data.
TABLE-US-00001 TABLE 1 Identification Flags Number of questions
Number of answer RRs Number of authority RRs Number of additional
RRs Service TYPE User Authentication Data Questions (variable
number of questions) Answers (variable number of resource records)
Authority (variable number of resource records) Additional
information (variable number of resource records)
TABLE-US-00002 TABLE 2 Identification Flags Number of questions
Number of answer RRs Number of authority RRs Number of additional
RRs Questions (variable number of questions) Answers (variable
number of resource records) Authority (variable number of resource
records) Additional information (Service TYPE) Additional
information (User Authentication Data)
[0107] In addition, at least one of the service ID and the user
information may also be sent in a form different from the Question
message, or sent as a single message.
[0108] Furthermore, a message may carry multiple service IDs and
user information.
[0109] In Step S302, the DNS server selects at least one
appropriate IP address for the terminal according to the service ID
and/or the user information.
[0110] In particular, when receiving the service ID, the DNS server
selects at least one IP address corresponding to a network
equipment capable of providing the service for the terminal from
multiple IP addresses corresponding to the domain name needed to be
parsed, and further selects at least one IP address corresponding
to a network equipment having a low load. When receiving the user
information, the DNS server selects at least one IP address
corresponding to a network equipment that allows a user to access
from multiple IP addresses corresponding to the domain name needed
to be parsed, and further selects at least one IP address
corresponding to a network equipment having a low load. The above
described is also a technical means that guarantees network
security.
[0111] In Step S303, the DNS server returns the selected IP address
to the terminal.
[0112] In practical applications, the DNS server may exist as an
Answer message. The Answer message includes at least one RR in the
form of a four-tuple. Each RR may have a TTL indicating that the IP
address is valid or that the terminal should store the RR.
[0113] In addition, in order to prevent a network attacker from
using the DNS server identity to return an unreal or a hazard IP
address to the terminal, the DNS server adds authentication data in
the Answer message. After the terminal passes the authentication of
the authentication data, it is determined that the Answer message
is sent by the DNS server; otherwise, the Answer message is
discarded or used in other processes. The authentication data is
carried in the head part of the Answer message as listed in Table
3, or carried in the body part of the Answer message as listed in
Table 4, as Server Authentication Data. Moreover, the
authentication data may also be provided to the terminal as a
single message.
TABLE-US-00003 TABLE 3 Identification Flags Number of questions
Number of answer RRs Number of authority RRs Number of additional
RRs Service TYPE Server Authentication Data Questions (variable
number of questions) Answers (variable number of resource records)
Authority (variable number of resource records) Additional
information (variable number of resource records)
TABLE-US-00004 TABLE 4 Identification Flags Number of questions
Number of answer RRs Number of authority RRs Number of additional
RRs Questions (variable number of questions) Answers (variable
number of resource records) Authority (variable number of resource
records) Additional information (Service TYPE) Additional
information (Server Authentication Data)
[0114] In Tables 3 and 4, the Service TYPE is optional, and if it
exists, the value of the Service TYPE is the same as that in the
Question message sent by the terminal.
[0115] In the above embodiment, if the DNS query request sent by
the terminal carries the service ID, the DNS query request may
carry other related information, so as to ensure that the DNS
server may accurately provide the IP address corresponding to the
network equipment required to be accessed. For example, the mail
address of a user is zhangsan@sina.com, but the actual hostname of
the mail server may be pop.sina.com. When setting up the mail
account, the user just inputs the address "zhangsan@sina.com" and
the password, and does not need to input the hostname
"pop.sina.com" of the mail server. When receiving and sending
mails, the terminal provides the "sina.com" information to the DNS
server, and indicates the service type of the mail in the Service
TYPE. According to the indicated service type of the mail and the
"sina.com" information, the DNS server knows that it is the domain
name of the mail server "pop.sina.com" that the terminal requests
to parse, and then the DNS server parses the pop.sina.com. From the
above example, if the terminal provides the service type and
related information to the DNS server, the setting of some
information like the domain name of the mail server can be omitted
in the previous setup process, which brings much convenience to the
terminal.
[0116] An example of a practical application of the domain name
parsing method is illustrated as follows. In this example, it is
assumed that a user is a subscriber of China Mobile, and China
Mobile provides many brand services for the subscribers, such as
GoTone, M-zone, and Easyown. When the subscriber visits the same
Portal domain name, the DNS server selects an IP address of the
related service and provides the IP address to the subscriber
according to a service request from the subscriber. It is assumed
that the subscriber selects the service types of Multimedia
Messaging Service (MMS) and Push to Talk over Cellular (POC).
Related information about the two types of services is listed in
Table 5.
TABLE-US-00005 TABLE 5 User Service Service authentication Domain
name IP address port ID data www.chinamobile.com 202.10.2.12 10001
POC User name + password 202.10.2.13 10002 MMS User name +
password
[0117] A domain name parsing process is illustrated in FIG. 4,
which includes the following steps.
[0118] In Step S401, a terminal sends a DNS query request to a DNS
server, where the DNS query request carries a domain name
"www.chinamobile.com", service IDs of POC and MMS, and a user name
and password for each service.
[0119] In Step S402, the DNS server parses the domain name
"www.chinamobile.com", and selects the IP addresses "202.10.2.12"
and "202.10.2.13" respectively corresponding to the POC and MMS
after the user name and password are authenticated.
[0120] In Step S403, the DNS server returns the selected IP
addresses to the terminal, and provides corresponding service ports
to the terminal, the process respectively proceeds to Step S4041
and Step S4042.
[0121] In Step S4041, the terminal gets access to a network
equipment that provides the POC service according to the received
IP address of "202.10.2.12".
[0122] In Step S4042, the terminal gets access to a network
equipment that provides the MMS service according to the received
IP address of "202.10.2.13".
[0123] It should be noted that, in the above embodiment of the
domain name parsing method, if the DNS server cannot parse the
domain name or cannot locally find the IP address corresponding to
the domain name, two solutions, namely, iterative parsing and
recursive parsing are provided below. In the iterative parsing, in
case of failing to find the corresponding records, the server
returns the address of another DNS server that probably knows the
result to the terminal, so that the terminal sends the DNS query
request to the new DNS server. In the recursive parsing, the system
composed of all the DNS servers is required to provide the parsing
result as a whole, i.e., if the parsing result cannot be acquired
from one of the DNS servers, the DNS server sends the DNS query
request to the other DNS servers, until the query result is
acquired or an error occurs.
[0124] The domain name is parsed from top to bottom according to
the hierarchical structure. However, if each parsing request starts
from the root server, the information flow reaching the root server
increases along with the expansion of the scale of the Internet,
which causes that the root server is overloaded due to the heavy
load. Generally speaking, in most cases of parsing the domain name,
the local domain name is parsed, which can be done at the local DNS
server. Therefore, when the terminal intends to obtain IP addresses
corresponding to a certain domain name, the terminal usually first
sends a DNS query request to the local DNS server, which improves
the efficiency of parsing the domain name.
[0125] For example, a host cs.nankai.edu.cn queries the IP address
of a host www.sina.com.cn, and the querying process where the
iterative parsing is adopted is shown in FIG. 5. The host
cs.nankai.edu.cn first sends a DNS query request to a local DNS
server (Step S501). After receiving the DNS query request, the
local DNS server searches for records locally. If it fails to find
the corresponding record, the local DNS server sends an iterative
parsing request to its own root domain server (Step S502). If the
root domain server cannot parse, the address of a DNS server that
manages the en domain is returned (Step S503). The local DNS server
hands over the DNS query request to the DNS server that manages the
en domain (Step S504). If the DNS server that manages the en domain
cannot parse, the address of a DNS server that manages the com.cn
domain is returned (Step S505). The local DNS server hands over the
DNS query request to the DNS server that manages the com.cn domain
(Step S506). If the DNS server that manages the com.cn domain
cannot parse, the address of a DNS server that manages the
sina.com.cn domain is returned (Step S507). The local DNS server
then hands over the DNS query request to the DNS server that
manages the sina.com.cn domain (Step S508). The DNS server that
manages the sina.com.cn domain returns a parsing result to the
local DNS server (Step S509). The local DNS server returns the
parsing result to the terminal (Step S510).
[0126] All the embodiments of the domain name parsing method can be
accomplished by a device, and thus the embodiment of the present
invention provides a domain name parsing device. The device
includes: a DNS query request receiving unit, adapted to receive a
DNS query request sent by a terminal, where the DNS query request
carries at least one of a service ID for identifying a service type
and user information for identifying a user ID; an IP address
selecting unit, adapted to select at least one IP address for the
terminal according to at least one of the service ID and the user
information received by the DNS query request receiving unit; and
an IP address providing unit, adapted to provide the IP address
selected by the IP address selecting unit to the terminal.
[0127] The above embodiment of the domain name parsing device is
applicable to a DNS serve, and thus the embodiment of the present
invention further provides a DNS server. The DNS server includes: a
DNS query request receiving unit, adapted to receive a DNS query
request sent by a terminal, where the DNS query request carries at
least one of a service ID for identifying a service type and user
information for identifying a user ID; an IP address selecting
unit, adapted to select at least one IP address for the terminal
according to at least one of the service ID and the user
information received by the DNS query request receiving unit; and
an IP address providing unit, adapted to provide the IP address
selected by the IP address selecting unit to the terminal.
[0128] In addition, the embodiment of the present invention further
provides a domain name parsing result acquisition method. The
method includes: sending a DNS query request to a DNS server, where
the DNS query request carries at least one of a service ID for
identifying a service type and user information for identifying a
user ID; and receiving at least one IP address provided by the DNS
server, where the at least one IP address is selected by the DNS
server for the terminal according to at least one of the service ID
and the user information.
[0129] Correspondingly, the above embodiment of the domain name
parsing result acquisition method may be accomplished by a domain
name parsing result acquisition device. The device includes: an
information loading unit, adapted to load at least one of a service
ID for identifying a service type and user information for
identifying a user ID to a DNS query request; a DNS query request
sending unit, adapted to send the DNS query request loaded with at
least one of the service ID and the user information to a DNS
server; and an IP address receiving unit, adapted to receive at
least one IP address provided by the DNS server, where the at least
one IP address is selected by the DNS server for the terminal
according to at least one of the service ID and the user
information.
[0130] The above domain name parsing result acquisition method is
applicable to a terminal, and thus the embodiment of the present
invention further provides a terminal. The terminal includes: an
information loading unit, adapted to load at least one of a service
ID for identifying a service type and user information for
identifying a user ID to a DNS query request; a DNS query request
sending unit, adapted to send the DNS query request loaded with at
least one of the service ID and the user information to a DNS
server; and an IP address receiving unit, adapted to receive at
least one IP address provided by the DNS server, where the at least
one IP address is selected by the DNS server for the terminal
according to at least one of the service ID and the user
information.
[0131] In all the embodiments of the domain name parsing method
according to the present invention, after the DNS query request
that carries at least one of the service ID and the user
information is received, an appropriate IP address is selected for
the terminal according to at least one of the service ID and the
user information, thus avoiding the circumstance that the selected
IP address is inappropriate as the terminal is not taken into
account, and solving the problem of selecting the appropriate IP
address for the terminal when the terminal is taken into
account.
[0132] In all the embodiments of the domain name parsing method
according to the present invention, the DNS query request may be in
the form of a Question message, and may be accomplished by adding
at least one of the service ID and the user information in at least
one of the head part and the body part of the Question, which is
relatively convenient in implementation.
[0133] In all the embodiments of the domain name parsing method
according to the present invention, when the selected IP address is
returned to the terminal, authentication data for security
authentication may also be provided to the terminal. In this
manner, the terminal may perform authentication on the
authentication data, so as to prevent a network attacker from using
the DNS server identity to return a hazard IP address to the
terminal, thereby enhancing the network security.
[0134] In all the embodiments of the domain name parsing method
according to the present invention, if the at least one IP address
cannot be selected for the terminal according to at least one of
the service ID and the user information, other DNS servers are
requested for help, and the addresses of the other DNS servers are
returned to the terminal. The terminal sends the same DNS query
request to the other DNS servers according to these addresses,
which guarantees the terminal to obtain the desired IP address to
the maximum extent.
[0135] In the above embodiments of the method, device, and terminal
for storing the DNS records, if it is determined that the size of
all the stored DNS records does not satisfy the preset storing
threshold, a part of the DNS records is deleted to enable the size
of the remaining DNS records to satisfy the storing threshold. In
this manner, the problem that the excessive storage of the DNS
records may influence the storage of other data is solved for
terminals with a small storage capacity.
[0136] In the above embodiments of the method, device, and terminal
for storing the DNS records, after the DNS query request that
carries at least one of the service ID and the user information is
received, an appropriate network address corresponding to the
domain name is selected for the terminal according to at least one
of the service ID and the user information, thus avoiding the
circumstance that the selected network address is inappropriate as
the terminal is not taken into account, and solving the problem of
selecting the appropriate network address for the terminal when the
terminal is taken into account.
[0137] The preferred embodiments of the present invention are
described above. It should be noted that, persons of ordinary skill
in the art can make some modifications and variations without
departing from the spirit of the present invention, and the
modifications and variations also fall within the scope of the
invention.
* * * * *
References