| 摘要 |
PROBLEM TO BE SOLVED: To save a negative cache for an appropriate period.SOLUTION: When a cache DNS server 20 receives a response that name resolution is impossible from an authority DNS server 10, a domain name included in a DNS query request is stored, as a domain name impossible of name resolution, in a DNS cache information storage section, and a cache period determined corresponding to the domain name is stored in the DNS cache information storage section. When the cache DNS server 20 determines that a domain name included in the DNS query request has been stored in the DNS cache information storage section, a cache period stored in the DNS cache information storage section and corresponding to the domain name is extended. |
