Network connection system and connection substitute correspondence client

A network connection system, comprising:

• a first organization with a host machine having a formal address;
• a plurality of second organizations, each with a host machine having either an informal address or a local address;
• a connection substitute server substituting a connection between the host machine belonging to the first organization and the host machine belonging to one of the plurality of second organizations and having no formal address and relaying information;
• a name server in which, as registration information regarding the host machine belonging to the one of the plurality of second organizations and the connection substitute server of the second organization corresponding thereto, the name server comprising
• a first record of an address including
• first host retrieval information in which a domain name is coupled with a host name of the one of the second organizations,
• first kind information showing that the registration information is an address, and
• an address of the host of the one of the second organizations,
• a second record of an address including
• second host retrieval information in which a domain name is coupled with the host name of the one of the second organizations,
• second kind information showing that the registration information is the connection substitute server, and
• connection substitute server retrieval information in which a domain name is coupled with a host name of the connection substitute server of the one of the second organizations, and
• a third record of an address including
• third host retrieval information in which a domain name is coupled with the host name of the connection substitute server of the one of the second organizations,
• third kind information showing that the registration information is the address, and
• an address of the connection substitute server of the second organization have been registered, and
• when a retrieval request using the host retrieval information of the one of the second organizations is received, in the retrieval at the first stage, connection substitute server retrieval information is obtained from said second record of the address, and in the retrieval at the second stage, the address of the second organization is obtained from said third record of the address by the connection substitute server retrieval information obtained by the retrieval at said first stage and responded to a request source.