•
Question
I have some inquiries regarding DHCP and DNS and would like to clarify them.
1. With DHCP, we can access to the DHCP server through DHCP relay agent(s), so we don't have to get every link a DHCP server, but is it essential to have at least one DHCP relay agent in every link?
2. Theoretically, DNS "translates" the IP address of a certain website into URL with domain name inside, so I tried to type the IP address i got from nslookup instead of the URL to see if I can reach to the site. Unfortunately I failed, may i know is there any specific reason to cause this failure?
Please correct me if I have misunderstood anything
•
Answerd by Professor Hygon Kim
1. Yes, there must be a DHCP relay agent on every link if you want to have the DHCP server on a remote location. Usually routers assume that role.
2. For IP to domain name translation, there must be a mapping stored in the DNS system. It is the PTR RR.
Even if you have a domain name to IP mapping, i.e. A RR, it does not mean that there is a PTR RR that has the inverse mapping. You must create it separately. The reason that you failed it that there was no PTR RR.