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I have a Windows Server 2016 (Datacenter Core) running DHCP server role which is not responding to DHCP requests which come from a DHCP relay but is responding to DHCP requests on the local network.

The server running the DHCP role has an ip address of 172.31.2.100/16.

The DHCP relay is a pfSense router with two adapters and addresses 172.31.255.254/16 and 172.30.255.254/16 and is configured to relay DHCP requests from the 172.30.x.x subnet to 172.31.2.100.

Running netsh on the server shows the DHCP requests arriving with the relay agent field correctly populated (172.30.255.254) but the DHCP event log doesn't show any activity.

The DHCP server is fine handing out leases on the local network.

Manually setting an IP for a host in the 172.30.x.x range works and when that's done it can ping the DHCP server and the DHCP server can ping it so the router is doing its job fine.

DHCP Server configuration: DHCP Server configuration

DHCP Scope options: enter image description here

Packet capture (from DHCP server): Packet capture (from DHCP server)

DHCP Server event log: DHCP Server event log

The DHCP Relay configuration: DHCP Relay configuration

Am I doing something obviously dumb?

  • Please post a screen shot of the Relay settings. – Davidw Sep 12 '17 at 19:45
  • Added! Does something look off in the forwarded DHCPDISCOVER? – digitalPhonix Sep 13 '17 at 1:49
  • I'm not familiar with reading Microsoft Message Analyzer captures, what's in the GIADDR field in the DHCPDISCOVER? That'll be used by the DHCP server to select the appropriate Scope from which to offer an ip address. If it's wrong it may be that you have the DHCP relay agent bound to the wrong interface on the pfSense. – joeqwerty Sep 13 '17 at 2:45
  • The log shows pool exhausted. – Davidw Sep 13 '17 at 2:46
  • @Davidw: I'm not seeing that. I see Event ID's 24, 25, and 11. Lines/Messages 1 through 30 are descriptive/informational. The actual log entries start at Line/Message 31. – joeqwerty Sep 13 '17 at 2:58

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