设计一个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，三种检索结果：

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）

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）

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）

考虑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-Design a DNS server program that reads " domain-IP address"　table, when the client queries the domain name corresponding to the IP address, the domain name to retrieve the table, three search results: Search results for the ip address 0.0.0.0, the returned to the client " domain name does not exist"　error message (bad site blocking features) search results as ordinary IP address, this address is returned to the client (server function) table is not seized to the domain name, then issue a query to the Internet DNS server , and the results back to the client (relay) to consider the client multiple computers simultaneously query, you need to convert the message ID