DNS vs. DHCP

I apologize if everyone thinks this is in the wrong forum, but I had a question that came up last night that my mind was telling me I was right but I couldn't get over the possibility that I could be wrong.

A DNS server could be on a different subnet when configured on a host but a DHCP server has to be on the same subnet.

The above statement is correct right? The reasoning would be the host broadcasts to a DHCP server and receives the DNS information (possibly) from that reply.

Any help would be appreciated.

Find more posts tagged with

Save $250 on 2025 certification boot camps from Infosec!

Book now with code EOY2025

Button

Comments

meadIT

Both DNS and DHCP could be on any subnet. If you do not have a DHCP server on your subnet, you do need a DHCP relay agent though (can be a RFC 1542 compliant router or another computer acting as the agent). The Relay Agent just acts as a middle man. It picks up the DHCP Discover broadcast packet and forwards it to the DHCP server.

APA

technically no... the DHCP server can be in a different subnet...

It's a matter of turning the DHCP broadcast into a unicast request...

On Cisco devices you can utilize the 'ip helper-address x.x.x.x' command on a gateway interface to tell the router to forward all DHCP broadcasts as unicast requests to the host specified.

Traditionally you would put a DHCP server in the local lan to negate the need to use 'ip helper-address'.... but to answer your question... it is possible to have a DHCP server in a different subnet.

jscimeca715

That's why this site is the bomb. Thanks guys.