Could someone explain to me the difference between using a router as a DHCP relay agent (option 82) and configuring option 3 (routers option) on the DHCP server? I currently need to set up a server to use option 3 to reproduce an issue in a test environment but I need a good "real-life" scenario to assist. Would it be something like this for option 3?
DHCPclient >>>>>>> Remote router >>>>>>> DHCP Server Where the "DHCP Server" would send the "Remote Router" client-side IP address in the option 3 section of the DHCP Offer ? Or does the the remote router need to be set as a relay-agent to have this make sense?
Would it ever make sense to have:
DHCPclient>>>>>>>DHCP Server, where Option 3 is still necessary in the DHCP Offer? ie: Option 3 contains the DHCP Server's client side address?
I already know how to set up option 3 and relay agents / helper ip address but just need more on the theory of the option 3 and the scenarios where it would be used. Any help on this would be appreciated.