DHCP Server on a different subnet

redgunnerredgunner Member Posts: 42 ■■□□□□□□□□
in CCNA & CCENT
Hello,



How do I allow my 2PCs on 172.16.0.0 subnet recognise that my DHCP Server on 192.168.1.0 subnet is there and is wanting to share a range of IPs? Thanks for your help in advance as always! :)
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Comments

  • 4_lom4_lom Member Posts: 485
    You need to add a DHCP relay on your router.

    See here for more details:

    DHCP - Configuring the Cisco IOS DHCP Relay Agent  [Support] - Cisco Systems
    Goals for 2018: MCSA: Cloud Platform, AWS Solutions Architect, MCSA : Server 2016, MCSE: Messaging

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  • Ltat42aLtat42a Member Posts: 587 ■■■□□□□□□□
    Here's an example done in Packet Tracer -
    https://www.youtube.com/watch?v=56Q-w0cY6NI
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  • satishtechsatishtech Member Posts: 243
    R3(config)#interface of 172.16.0.0/16 subnet
    R3(config-if)#ip helper-address dhcp-server-ip
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  • redgunnerredgunner Member Posts: 42 ■■□□□□□□□□
    Thanks for this - Got it working.

    Does IP Helper Address listen for particular ports or is it all ports? For example, could I block DNS or maybe a webserver port?
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  • satishtechsatishtech Member Posts: 243
    DHCP Ports

    67 UDP DHCP-SERVER bootps
    68 UDP DHCP-CLIENT bootpc

    extended ACL blocking port 67 may work.
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  • redgunnerredgunner Member Posts: 42 ■■□□□□□□□□
    Without focusing on ACL Lists / Firewalls etc...

    What ports does ip helper address listen for?
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