Brand new to networking and trying different scenarios.

PC2 can successfully send packets to PC1 and the DHCP server if a static address is assigned. However, PC2 will not obtain a DHCP address from the server.

I'm assuming at this point, a helper address is required, but I'm not sure which switch or router that should be defined on

Note: All devices are on Vlan 1 - DHCP is configured correctly for 64 subnet

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2 Answers 2


You configure the helper aka DHCP relay with the address of the DHCP server. The helper needs to be share a broadcast domain with the DHCP client.

In your diagram, you need to configure the helper on Router B / Gig0/0/0 and point it at Obviously, the DHCP server needs to have a configured scope for

  • It appears that the helper-address had to be entered AFTER the static routes were assigned. I'm not sure why, but it seemed to have worked.
    – prosportal
    Commented Feb 16, 2023 at 2:54
  • I need proper routing between the DHCP relay and the server, obviously.
    – Zac67
    Commented Feb 16, 2023 at 7:47

Router B. Int G0/0/0. This will forward the DHCP traffic.

  • Helper address will be the address of your DHCP server.
    – user87528
    Commented Feb 15, 2023 at 21:10
  • 1
    To provide a little more info. Routers are designed to block broadcast traffic. DHCP Requests are broadcast traffic. So you need to add the helper address to forward that traffic.
    – user87528
    Commented Feb 15, 2023 at 21:13
  • 1
    Routers don't "block broadcast traffic"; they don't forward broadcast traffic, because it's supposed to be link-local. The helper-address tells the router to enable it's DHCP Relay Agent, and what DHCP server to use.
    – Ricky
    Commented Feb 16, 2023 at 2:32

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