DNS-Server

Implemented a simplified DNS system consisting of a Client program and two server programs:
RS (a simplified root DNS server) and TS (a simplified top-level DNS server)

The Client program has two sockets: one used to communicate with the RS server and the other is for the TS server

The RS and TS programs each maintain a DNS_table consisting of three fields:

• Hostname
• IP address
• Flag (A or NS)

Program Outline:

1. Client connects to the RS sever, sending the queried hostname as a string
2. The RS program does a look up in its DNS_table, and if there is a match, sends the entry as a string:
   Hostname IPaddress A
3. If there is no match, RS sends the string: TSHostname - NS
   (where TShostname the machine hosting TS)
4. The client then sends the queried hostname as a string to TS
5. The TS program looks up the hostname in its DNS_table, and if there is a match, sends the entry as a string: Hostname IP address A
   Otherwise, it sends an error string: Hostname - Error: HOST NOT FOUND