In Cisco Packet Tracer I created following network

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Following is how I configured the DHCP Server

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But the computers can't get IP addresses - getting "DHCP failed" message. Why? Please explain. What should I do so that PCs got dynamic IP addresses from the server?

1 Answer 1


The DHCP server must be in the same layer 2 network as the devices that will require its service availability.

If you want a DHCP server to function on the other side of a layer 3 boundary (router) then you need to configure a DHCP helper service on the gateway device for the networks in question. Your ISR router would need to provide the DHCP Helper role to allow the client devices on the network on the left side of the diagram to receive DHCP offers from the server on the right side of the diagram.

  • A DHCP relay can be configured on any device within the clients' broadcast domain, e.g. on the switch.
    – Zac67
    Oct 27, 2022 at 5:02
  • @Zac67, Yeah, I found this video at youtube. Oct 27, 2022 at 5:25
  • @DotNetDeveloper We won't explain any Youtube videos for you here. Please add the relevant infos to your question. As it is, Jonathan's answer does just fine.
    – Zac67
    Oct 27, 2022 at 6:13
  • @Zac67, Jonathan's answer is incomplete. He has to provide instructions to resolve the issue. Now he has only pointed to what to do. Oct 27, 2022 at 7:04
  • Sorry, but an answer does not need to provide complete instructions, especially when there's very little to work with (you haven't provided complete configs from either 2960 or ISR). Jonathan's reply answers your question "what should I do" on an adequate level.
    – Zac67
    Oct 27, 2022 at 9:21

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