US20100042725A1 - Contents provider participation type contents delivery system and method, and contents delivery network domain name system server thereof - Google Patents

Abstract

A CP participated contents delivery system and method, and a CDN DNS server of the system are provided. When a client detects an embedded object while parsing a page received from a web server, the client inquires of a local DNS server about the IP address of a server storing the object. The local DNS server receives the inquiry of the client and inquires of a CDN DNS server about the IP address of the server storing the object. The CDN DNS server selects a server located in proximity to the client from a host server of a CDN provider, which stores the object, and the web server. The selected server transmits the object to the client. Accordingly, the client can rapidly receive the object and a contents provider can promote qualitative contents providing service improvement.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a contents delivery network (CDN) including globally deployed replica servers, and more particularly, to a contents provider (CP) participated contents delivery system and method for allowing a web server of a CP to function as a replica server of a CDN for a client located in proximity to the web server to directly provide contents to the client, and a CDN domain name system (DNS) server of the system.
• 2. Description of the Related Art
• A web server of a contents provider (CP) generally provides a large number of contents (for example, videos, music, files, etc.) to clients. A large load is generated when the web server provides the whole or some of the contents to a plurality of clients one to one because the plurality of clients exist in a plurality of Internet service providers (ISPs) while the web server is connected to a single ISP.
• Accordingly, traffic between ISPs exponentially increases as the number of contents providers and clients increase, and thus transmission delay and/or transmission failure rate due to traffic congestion increase. Web server fail-over may occur in the worst case.
• To solve this problem, a contents delivery network (CDN) is introduced. The CDN is a service which previously stores contents converging on a web server of a contents provider located at a great distance from clients, for example, contents with large capacity, such as pictures, banners, videos or audio, or contents frequently requested by clients, in host servers globally deployed at points of presence (PoP) of a plurality of ISPs and redirects the path of the host server closest to a client when the client requests the contents provider to provide contents such that the client accesses the host server through the redirected path to be provided with the contents. Here, the host server may be referred to as a cache server, a replica server or a ghost server.
• The CDN is classified into an overlay type and a network type according to system configuration. In the overlay type CDN, a server for a special purpose and a plurality of cache servers manage distribution of contents. The overlay type CDN has an advantage of simple administration because there is no need for a CDN provider to control network lower layer. In the network type CDN, network components such as a router and a switch include codes for confirming a specific application type and forwarding requests of clients according to a predetermined policy.
• Recently, most of solutions of CDN providers have adopted mixture of the overlay and network types. An example of mixture of the two types is disclosed in U.S. Pat. No. 6,108,703 (Referred to as '703 patent hereinafter) entitled “Global hosting system”, issued to F. Thomson Lieghton et al., and assigned to MIT (Messachusetts Institute of Technology).
• According to the '703 patent, a web server of a contents provider provides a page including a uniform resource locator (URL) (referred to as ‘modified URL’ hereinafter) of an embedded object, which is modified according to a special routine, in response to a request of a client. The web browser of the client loads the embedded object in order to display the page. The '703 patent identifies the modified URL through hierarchical DNS servers called a first level name server and a second level name server and returns the IP address of the optimum host server capable of providing the actual object to the client.
• The '703 patent uses so-called DNS-based request routing. Although general DNS-based request routing has a problem that network latency according to DNS look-up time is aggravated, the '703 patent decreases network latency by constructing hierarchical DNS servers.
• However, even when the client is located in proximity to the web server of the contents provider, that is, when the client and the web server of the contents provider are close to each other geographically or on a network route, the DNS-based request routing is performed, which is inefficient.
• Accordingly, a method for solving the aforementioned problems is required.
SUMMARY OF THE INVENTION
• An object of the present invention is to allow a DNS server of a CDN provider to perform routing such that a web server operated by a contents provider to directly provide contents such as page embodied objects to a client who requests the contents through a network of the CDN provider when the client is located in proximity to the web server so as to provide improved quality of service (QoS) to the client and decrease useless network load.
• To accomplish the object of the present invention, according to an aspect of the present invention, there is provided a contents provider (CP) participated contents delivery system including: at least one host server receiving and storing an object embedded in a page and transmitting the object to a client at the request of the client; a web server storing the page and the object, transmitting the object to the at least one host server such that the at least one host server stores the object, and transmitting the page or the object to the client at the request of the client; and a CDN DNS server selecting a server located in proximity to the client from the at least one host server and the web server and transmitting the IP address of the selected server to the client through a local DNS server at the client when inquiry about the IP address of a server storing the object is received from the local DNS server.
• The CDN DNS server may select the server located in proximity to the client with reference to the IP address of the client.
• The CDN DNS server may select another server located in proximity to the client when the data traffic of the selected server exceeds a critical value.
• According to another aspect of the present invention, there is provided a CDN DNS server including: a transmitting/receiving unit for transmitting/receiving data; a database storing IP addresses of at least one host server storing an object embedded in a page and a web server providing the page and the object; a determination module determining proximity of an arbitrary client to at least one of the at least one host server and the web server; and a controller selecting a specific server which will transmit the object to the client receiving the page through the transmitting/receiving unit from the at least one host server and the web server with reference to the determination result of the determination module and transmitting the IP address of the specific server to the client through the transmitting/receiving unit via a local DNS server at the client with reference to the IP addresses stored in the database when inquiry of the local DNS server about the IP address of a server storing the object is received.
• The determination module may determine the proximity of the client to at least one of the at least one host server and the web server with reference to the IP address of the client.
• The controller may select another server located in proximity to the client when data traffic of the selected server exceeds a critical value.
• According to another aspect of the present invention, there is provided a CP participated contents delivery method including: a storing step in which at least one host server receives an object embedded in a page from a web server and stores the object embedded in the page; a page transmitting step in which the web server requested by a client to provide the page transmits the page to the client; and an address transmitting step in which a CDN DNS server selects a server located in proximity to the client from the at least one host server and the web server and transmits the IP address of the selected server to the client through the local DNS server when receiving inquiry about the IP address of a server storing the object is received from a local DNS server at the client receiving the page.
• In the address transmitting step, the CDN DNS server may select the server with reference to the IP address of the client.
• The address transmitting step in which the CDN DNS server receives the inquiry about the IP address of the server storing the object may include a step in which the client inquires of the local DNS server about the IP address of the server storing the object by using a URL representing the position of the object detected while receiving and parsing the page.
• The address transmitting step in which the CDN DNS server receives the inquiry about the IP address of the server storing the object may include a step in which the local DNS server, which receives the inquiry of the client about the IP address, inquires of a contents provider DNS server about the IP address of the server storing the object, receives domain name information of a CDN provider from the contents provider DNS server and inquires of the CDN DNS server about the IP address of the server storing the object.
• The domain name information received by the local DNS server may be included in a canonical name (CNAME) record and received.
BRIEF DESCRIPTION OF THE DRAWINGS
• The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
• FIG. 1 is a configuration of a CP participated contents delivery system according to an embodiment of the present invention;
• FIG. 2 is a block diagram of a CDN DNS server illustrated inFIG. 1;
• FIG. 3 is a flowchart showing a CP participated contents delivery method according to an embodiment of the present invention; and
• FIG. 4 is a flowchart showing a CP participated contents delivery method according to another embodiment of the present invention
DETAILED DESCRIPTION OF THE INVENTION
• The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Throughout the drawings, like reference numerals refer to like elements.
• FIG. 1 illustrates a configuration of a CP participated contents delivery system according to an embodiment of the present invention. Referring toFIG. 1, the contents delivery system includes aclient110, a local domain name system (DNS)server120, ahost server130, aCDN DNS server140, a contentsprovider DNS server150, aweb server160 and anetwork170.
• Theclient110 corresponds to equipment such as a computer receiving information from the servers connected through thenetwork170. For example, theclient110 includes equipment which is currently commercially used or will be developed such as personal computers (PCs), household appliances, mobile communication devices, etc. in the current embodiment of the invention.
• Theclient110 includes a browser and a resolver. When a uniform resource locator (URL) that requests specific contents is input to the browser of theclient110, the resolver connected to the browser accesses the previously registeredlocal DNS server120 and resolves a domain name corresponding to the URL into the IP (Internet Protocol) address of theweb server160 providing the contents.
• In the current embodiment of the invention, when theclient110 receives a page from theweb server160 by using the IP address of theweb server160, theclient110 parses the page and inquires of thelocal DNS server120 about the IP address of a server which will provide an embedded object detected while the page is parsed by using the URL of the embedded object. Then, when theclient110 receives the IP address of theweb server160 or thehost server130, which will transmit the embedded object, from thelocal DNS server120, theclient110 accesses the corresponding server by using the IP address and receives the embedded object.
• Thelocal DNS server120 means a domain name server that transforms a domain name into an IP address and converts a symbolic name into a numeral address used by machines. Thelocal DNS server120 that receives the domain name of theweb server160 from the resolver accesses the contentsprovider DNS server150, receives the IP address of theweb server160, which corresponds to the domain name, and transmits the IP address to theclient110.
• When theclient110 requests thelocal DNS server120 to provide the IP address of the server storing the embedded object included in the page, thelocal DNS server120 transmits/receives messages to/from the contentsprovider DNS server150 or theCDN DNS server140 to transmit the IP address of theweb server160 or thehost server130 which will transmit the embedded object to theclient110.
• Thehost server130 stores replicas of page embedded objects stored in and administrated by theweb server160 and rapidly provides the replicas when theclient110 requests thehost server130 to provide contents.
• TheCDN DNS server140 is a DNS server of a CDN provider and provides the IP address of thehost server130 storing the embedded object at the request of thelocal DNS server120. The CDNDNS server140 of the present invention not only performs a general DNS server function but also selects thehost server130 efficient to provide the embedded object to theclient110 in consideration of at least one of data traffic information of at least onehost information130, information on proximity of theclient110 to the at least onehost server130 and object information stored in the at least onehost server130 and transmits the IP address of the selectedhost server130 to theclient110 through thelocal DNS server120.
• Here, the data traffic information of the at least onehost information130, the information on proximity of theclient110 to the at least onehost server130 and the object information stored in the at least onehost server130, considered by theCDN DNS server140, may be collected in consideration of data traffic and load of theCDN DNS server140 or thehost server130 when the object stored in thehost server130 is updated and at predetermined time such as a specific period.
• When theCDN DNS server140 receives inquiry of thelocal DNS server120 at theclient110 about the IP address of a server storing the page embedded object, theCDN DNS server140 selects a server located in proximity to theclient110 from the at least onehost server130 and theweb server160 which store the object and transmits the IP address of the selected server to theclient110 through thelocal DNS server120 such that theclient110 can receive the object from the selected server. That is, if theweb server160 is located in proximity to theclient110, and thus it is more efficient to provide the page embedded object by theweb server160 in terms of network route, theweb server160 provides the object to theclient110. If not, one of the at least onehost server130, which is located in proximity to theclient110 to be suitable to provide the object, is selected and provides the object to theclient110.
• Here, the server located in proximity to theclient110 may be selected with reference to the IP address of theclient110. However, when the data traffic of the server selected to provide the object to theclient110 exceeds a critical value, another server located in proximity to theclient110 may be selected and the IP address of the selected server may be transmitted to theclient110 through thelocal DNS server120.
• In this manner, theclient110 can receive the page embedded object through a network route providing a more rapid response and the CDN provider can dynamically determine the subject of object transmission in consideration of loads of thehost server130 and theweb server160 and network route.
• Theweb server160 provides a web page and an embedded object included in the web page, provided by the contents provider. In the current embodiment of the present invention, the contents provider transmits the embedded object from theweb server160 to thehost server130 such that thehost server130 stores the embedded object. Accordingly, when theclient110 requests the embedded object included in the page, theclient110 can rapidly receive a response through thehost server130.
• Thecontents DNS server150 is a DNS server of the contents provider. When the contentsprovider DNS server150 receives inquiry of thelocal DNS server120 about the IP address of theweb server160 storing the page, the contentsprovider DNS server150 returns the IP address.
• Furthermore, when the contentsprovider DNS server150 receives inquiry of thelocal DNS server120 about the IP address of a server storing the object included in the page, the contentsprovider DNS server150 transmits domain name information of the CDN provider to thelocal DNS server120 such that thelocal DNS server120 can inquire of theCDN DNS server140 about the IP address of the server storing the object.
• Here, the domain name information can be transmitted to thelocal DNS server120 through a canonical name (CANAME) method, for example. CNAME means DNS database record representing a host name. Thelocal DNS server120 can inquire of theCDN DNS server140 about the IP address of the server storing object by using the domain name information of the CND provider, which is included in the DNS database record.
• Thenetwork170 corresponds to a data communication network for data transmission and information exchange among theclient110, thelocal DNS server120, thehost server130, theCDN DNS server140, the contentsprovider DNS server150 and theweb server160. Thenetwork170 according to the present invention includes Internet, Intranet, Extranet, and other wired and wireless networks and a combination thereof, which are well-known or will be developed.
• The configuration and operation of theCDN DNS server140 according to an embodiment of the present invention will now be explained in more detail with reference toFIG. 2.
• FIG. 2 is a block diagram of theCDN DNS server140 illustrated inFIG. 1. Referring toFIGS. 1 and 2, theCDN DNS server140 includes a transmitting/receivingunit141, acontroller143, adatabase145 and adetermination module147.
• The transmitting/receivingunit141 has an interface for transmitting/receiving data and messages through thenetwork170.
• Thedatabase145 stores the IP addresses of the at least onehost server130 and theweb server160 which store page embedded objects provided by the web server.
• Thedetermination module147 determines proximity of theclient110 to the at least onehost server130 and theweb server160. Here, the proximity of theclient110 to at least onehost server130 and theweb server160 can be determined by using the IP address of theclient110.
• Thecontroller143 controls the operation of theCDN DNS server140. Specifically, thecontroller143 transmits the IP address of theweb server160 to theclient110 through the transmitting/receivingunit141 via thelocal DNS server120 if thedetermination module147 determines that the client is located in proximity to theweb server160 when thelocal DNS server120 inquires of theCDN DNS server140 about the IP address of a server storing a page embedded object.
• If thedetermination module147 determines that theclient110 is closer to thehost server130 than theweb server160, the controller transmits the IP address of thehost server130 to theclient110 through the transmitting/receivingunit141 through thelocal DNS server120.
• In this manner, theclient110 can receive the page embedded object from the server located in proximity thereto. If the selected server is not suitable to provide the object to theclient110 because the data traffic of the server exceeds a critical value although thedetermination module147 determines that the server is located in proximity to theclient110, thecontroller143 can transmit the IP address of another sever located in proximity to theclient110 to theclient110 through the transmitting/receivingunit141 via thelocal DNS server120 to attempt to distribute load of the server.
• Here, data traffic information of each server may be information collected by thecontroller143 through the transmitting/receivingunit141 at a specific period or information collected by thedetermination module147 through transmitting/receivingunit141 at a specific period and referred to by thecontroller143.
• A contents delivery method according to the present invention will be explained with reference toFIGS. 3 and 4.
• FIG. 3 is a flowchart showing a CP participated contents delivery method according to an embodiment of the present invention. Referring toFIG. 3, the at least onehost server130 receives an object embedded in a page of the contents provider from theweb server160 and stores the embedded object in step S400. Contents, that is, the embedded object, may be transmitted in step S400 when thehost server130 requests theweb server160 to provide the embedded object, at specific periods, and when the object embedded in the page stored in theweb server160 is updated.
• When the browser of theclient110 receives a URL for requesting theweb server160 to provide the embedded object, the resolver of theclient110 inquires of thelocal DNS server120 about the IP address of theweb server160 storing the page and the embedded object in step S405.
• Thelocal DNS server120 receives the inquiry about the IP address of theweb server160 in step S405 and inquires of the contentsprovider DNS server150 about the IP address of theweb server160 storing the page and the embedded object in step S410.
• The contentsprovider DNS server150 receives the inquiry of thelocal DNS server120 in step S410 and transmits the IP address of theweb server160 to thelocal DNS server120 in step S415. Thelocal DNS server120 receives the IP address of theweb server160 and transmits the IP address of theweb server160 to theclient110 in step S420.
• Theclient110 receives the IP address of theweb server160 in step S420 and requests theweb server160 to provide the page embedded object by using the IP address of theweb server160 in step S425.
• Theweb server160 receives the request of theclient110 in step S425 and transmits the page to theclient110 in step S430. Here, the URL representing the position of the embedded object stored in the page is rewritten into a URL representing the position of the embedded object stored in thehost server130 operated and administrated by the CDN provider.
• Theclient110 receives the page in step S430 and parses the page in step S435. When theclient110 detects the URL representing the position of the embedded object stored in the page while parsing the page, theclient110 inquires of thelocal DNS server120 about the IP address of a server storing the page embedded object by using the URL in step S440.
• Thelocal DNS server120 receives the inquiry of theclient110 in step S440 and inquires of theCDN DNS server140 about the IP address of the server storing the object in step S445.
• TheCDN DNS server140 receives the inquiry of thelocal DNS server120 in step S445 and determines proximity of theclient110 to the at least onehost server130 and theweb server160 in step S450. Here, theCDN DNS server140 can determine the proximity of theclient110 to the at least onehost server130 and theweb server160 with reference to the IP address of theclient110, for example.
• When theCDN DNS server140 determines that theclient110 is located in proximity to theweb server160 in step S450, theCDN DNS server140 transmits the IP address of theweb server160 to thelocal DNS server120 in step S455. Thelocal DNS server120 transmits the IP address of theweb server160, received in step S455, to theclient110 in step S460.
• Theclient110 requests theweb server160 to provide the object by using the IP address of theweb server160, received in step S460, and receives the object from theweb server160 in step S470.
• In the current embodiment of the present invention, if the data traffic of theweb server160 exceeds a critical value although it is determined that theclient110 is located in proximity to theweb server160 in step S450, the IP address of another web server or host server located in proximity to theclient110 can be transmitted to thelocal DNS server120 to prevent the load of theweb server160 from increasing.
• If theCDN DNS server140 determines that aspecific host server130 is closer to theclient110 than theweb server160 in step S450, theCDN DNS server140 transmits the IP address of thespecific host server130 to thelocal DNS server120 in step S475. Thelocal DNS server120 transmits the IP address of thehost server130, received in step S475, to theclient110 in step S480.
• Then, theclient110 requests thehost server130 to provide the object by using the IP address of thehost server130, received in step S480, in step S485 and receives the object from thehost server130 in step S490.
• In the current embodiment of the present invention, if the data traffic of thehost server130 exceeds a critical value although theCDN DNS server140 determines that theclient110 is located in proximity to thehost server130 in step S450, theCDN DNS server140 can transmit the IP address of theweb server160 or another host server located in proximity to theclient110 to thelocal DNS server120 to attempt load distribution.
• FIG. 4 is a flowchart showing a CP participated contents delivery method according to another embodiment of the present invention. InFIG. 4, steps S400 through S425 are identical to those of the contents delivery method illustrated inFIG. 3 so that detailed explanations thereof are omitted.
• Theweb server160 receives the request of theclient110 for the page embedded object in step S425 and transmits the corresponding page to theclient110 in step S500. The page transmitted in step S500 may be the original page in which the URL representing the position of the embedded object is not rewritten, which is distinguished from the embodiment described with reference toFIG. 3.
• Theclient110 parses the page, received in step S500, in step S505. When theclient110 detects the URL of the object embedded in the page while parsing the page in step S505, theclient110 inquires of thelocal DNS server120 about the IP address of a server storing the page embedded object by using the URL in step S510.
• Thelocal DNS server120 receives the inquiry of theclient110 in step S510 and inquires of the contentsprovider DNS server150 about the IP address of the server storing the object in step S515.
• The contentsprovider DNS server150 receives the inquiry of thelocal DNS server120 in step S515 and transmits domain name information of the CDN provider to thelocal DNS server120 in step S520. Here, the domain name information of the CDN provider may be included in CNAME resource record and transmitted, for example.
• Thelocal DNS server120 receives the domain name information in step S520 and inquires of theCDN DNS server140 about the IP address of the server storing the page embedded object by using the domain name information in step S525.
• TheCDN DNS server140 receives the inquiry of thelocal DNS server120 in step S525 and determines proximity of theclient110 to the at least onehost server130 and theweb server160 in step S530. Here, theCDN DNS server140 can determine the proximity of theclient110 to the at least onehost server130 and theweb server160 with reference to the IP address of theclient110, for example.
• When theCDN DNS server140 determines that theclient110 is located in proximity to theweb server160 in step S530, theCDN DNS server140 transmits the IP address of theweb server160 to thelocal DNS server120 in step S535. Thelocal DNS server120 transmits the IP address of theweb server160, received in step S535, to theclient110 in step S540.
• Theclient110 requests theweb server160 to provide the page em bedded object by using the IP address of theweb server160, received in step S540, in step S545 and receives the object from theweb server160 in step S550.
• In the current embodiment of the present invention, if the data traffic of theweb server160 exceeds a critical value although it is determined that theclient110 is located in proximity to theweb server160 in step S530, the IP address of another web server or host server located in proximity to theclient110 can be transmitted to thelocal DNS server120 to prevent the load of theweb server160 from increasing.
• If theCDN DNS server140 determines that aspecific host server130 is closer to theclient110 than theweb server160 in step S530, theCDN DNS server140 transmits the IP address of thespecific host server130 to thelocal DNS server120 in step S555. Thelocal DNS server120 transmits the IP address of thehost server130, received in step S555, to theclient110 in step S560.
• Then, theclient110 requests thehost server130 to provide the object by using the IP address of thehost server130, received in step S560, in step S565 and receives the object from thehost server130 in step S570.
• In the current embodiment of the present invention, if the data traffic of thehost server130 exceeds a critical value although theCDN DNS server140 determines that theclient110 is located in proximity to thehost server130 in step S530, theCDN DNS server140 can transmit the IP address of theweb server160 or another host server located in proximity to theclient110 to thelocal DNS server120 to attempt load distribution.
• According to the present invention, a client can receive a page embedded object from a server selected from a web server and at least one host server and located in proximity to the client. Accordingly, the client can rapidly receive the object and a contents provider can promote qualitative contents providing service improvement.
• While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims (11)

1. A contents provider (CP) participated contents delivery system comprising: at least one host server receiving and storing an object embedded in a page and transmitting the object to a client at the request of the client;

a web server storing the page and the object, transmitting the object to the at least one host server such that the at least one host server stores the object, and transmitting the page or the object to the client at the request of the client; and

a CDN DNS server selecting a server located in proximity to the client from the at least one host server and the web server and transmitting the IP address of the selected server to the client through a local DNS server at the client when inquiry about the IP address of a server storing the object is received from the local DNS server.

2. The CP participated contents delivery system ofclaim 1, wherein the CDN DNS server selects the server located in proximity to the client with reference to the IP address of the client.

3. The CP participated contents delivery system ofclaim 1, wherein the CDN DNS server selects another server located in proximity to the client when the data traffic of the selected server exceeds a critical value.

4. A CDN DNS server comprising:

a transmitting/receiving unit for transmitting/receiving data;

a database storing IP addresses of at least one host server storing an object embedded in a page and a web server providing the page and the object;

a determination module determining proximity of an arbitrary client to at least one of the at least one host server and the web server; and

a controller selecting a specific server which will transmit the object to the client receiving the page through the transmitting/receiving unit from the at least one host server and the web server with reference to the determination result of the determination module and transmitting the IP address of the specific server to the client through the transmitting/receiving unit via a local DNS server at the client with reference to the IP addresses stored in the database when inquiry of the local DNS server about the IP address of a server storing the object is received.

5. The CDN DNS server ofclaim 4, wherein the determination module determines the proximity of the client to at least one of the at least one host server and the web server with reference to the IP address of the client.

6. The CDN DNS server ofclaim 4, wherein the controller selects another server located in proximity to the client when data traffic of the selected server exceeds a critical value.

7. A CP participated contents delivery method comprising:

a storing step in which at least one host server receives an object embedded in a page from a web server and stores the object embedded in the page;

a page transmitting step in which the web server requested by a client to provide the page transmits the page to the client; and

an address transmitting step in which a CDN DNS server selects a server located in proximity to the client from the at least one host server and the web server and transmits the IP address of the selected server to the client through the local DNS server when receiving inquiry about the IP address of a server storing the object is received from a local DNS server at the client receiving the page.

8. The CP participated contents delivery method ofclaim 7, wherein, in the address transmitting step, the CDN DNS server selects the server with reference to the IP address of the client.

9. The CP participated contents delivery method ofclaim 7, wherein the address transmitting step in which the CDN DNS server receives the inquiry about the IP address of the server storing the object comprises a step in which the client inquires of the local DNS server about the IP address of the server storing the object by using a URL representing the position of the object detected while receiving and parsing the page.

10. The CP participated contents delivery method ofclaim 8, wherein the address transmitting step in which the CDN DNS server receives the inquiry about the IP address of the server storing the object comprises a step in which the local DNS server, which receives the inquiry of the client about the IP address, inquires of a contents provider DNS server about the IP address of the server storing the object, receives domain name information of a CDN provider from the contents provider DNS server and inquires of the CDN DNS server about the IP address of the server storing the object.

11. The CP participated contents delivery method ofclaim 8, wherein the domain name information received by the local DNS server is included in a canonical name (CNAME) record and received.

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