| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a network system which easily controls the communication destination of a client. SOLUTION: A client 11 transmits a transmission destination mail address 'xyz jepr.co.jp' to a mail server 21 to inquire of a DNS server 31 the IP address of a transmission destination mail server 53. The DNS server 31 accesses a transmission destination DNS server 52 to acquire the IP address of the mail server 53 and returns it to the mail server 21. The mail server 21 adds a zone name '.junior.' of the client to this IP address and inquires of the DNS server 31 whether it has been registered in a DB file of a DNS server 41 or not. The DNS server 31 inquires of the DNS server 41, and the DNS server 41 permits the mail server 21 to transmit a mail through the DNS server 31 when discriminating that it has been registered.</p> |
