说明：  DNS服务器程序。读入“域名-IP地址”对照表，当客户端查询域名对应的IP地址时，用域名检索该对照表，并返回三种检索结果：① 检索结果为IP地址0.0.0.0，则向客户端返回“域名不存在”的报错消息（不良网站拦截功能）；② 检索结果为普通IP地址，则向客户返回这个地址（服务器功能）；③ 表中未检到该域名，则向因特网DNS服务器发出查询，并将结果返给客户端（中继功能）。并且，考虑到多个计算机上的客户端会同时查询，需要进行消息ID的转换。
(DNS server program. Read into the domain name-IP address table, when the client queries the domain name corresponding to IP address, domain name search of the table, and returns three search results: ① Search Results for IP address 0.0.0.0, to the client returns " domain does not exist" error message (bad site blocking feature) ② search results for ordinary IP address, then returned to the client address (server function) ③ The table does not check to the domain name to the Internet DNS server issue a query and return the results to the client (relay function). And taking into account the client on multiple computers query the need for the conversion of the message ID.)