What is the difference between giaddr field in DHCP response and DHCP option 3?

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I have a DHCP client that I've used for years. Until now, it has always gotten its gateway IP address from DHCP Option #3. Now running with a new DHCP server that does not provide option 3 (yes I know its an option), so is the client supposed to use the giaddr field of the DHCP response? The RFCs talk about giaddr being a relay agent, but other places I read says it can be the gateway IP. What is the difference between the two fields?

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urutech On

The difference between giaddr and option 3 is that giaddr is read by the DHCP server and defines to what IP address the DHCP server sends the response to. Option 3 defines what is transmitted within the response as the gateway (router) address from server to client.

If you change the DHCP server and that new server does not send the option 3, then I‘m sure it‘s a matter of configuration. It would be a very strange DHCP server that does not support sending the gateway IP address, when configured.