| 摘要 |
PROBLEM TO BE SOLVED: To solve a terminal fallback problem in an IPv4/IPv6 dual stack environment to be accessible to a web server which can be accessed only by the IPv6, while reducing a waiting time to the possible extent.SOLUTION: It is discriminated whether or not a direct access to the Internet by the IPv6 with the prefix of an IPv6 address. When both an IPv4 address and an IPv6 address exist in a DNS response of a DNS query which is received from a terminal 12 and transferred to a DNS server 13, an IPv4 address and an IPv6 address corresponding to the DNS query are registered into a v6v4 combination table 25. Then, an IPv6 access from the terminal 12 to the server corresponding to the DNS query is relayed after v6v4 NAPT conversion is performed according to the record of the v6v4 combination table 25. |
