Cdnetworks Co., Ltd.

Yong-Bae Kim

Seok Lee

Seung-Ho Ryu

Disclosed are a method and an apparatus for calculating a distance in a contents delivery network. According to one preferred embodiment of the present invention, when a domain name resolution request is received from an LDNS, an identifier is added to a domain name requested to be resolved so as to create a CNAMEd domain name response, the CNAMEd domain name response is transmitted to a probe server, the CNAMEd domain name response transmitted to the probe server is transmitted to the LDNS after a source IP address thereof has changed into an address of a name server in the probe server, the name server receives a resolution request to the CNAMEd domain name response from the LDNS, and the name server determines, as a distance between the LDNS and a point of presence (POP), a value obtained by subtracting a distance between the name server and the LDNS and a distance between the name server and the probe server from an interval between a time for transmitting the CNAMEd domain name response from the name server to the probe server and a time for receiving, by the name server, the resolution request to the CNAMEd domain name response from the LDNS. According to the present invention, even when the probe server cannot calculate a distance to the LDNS, a distance between the LDNS and the POP can be calculated, and thus it is possible to improve and stabilize the quality of a contents delivery network service.

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Seoul, South Korea

Yong-Bae Kim