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Is there a way on Cisco layer 3 switches to show the DHCP server's IP address for every VLAN?

O_O
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  • Do you mean the helper addresses? – Ron Maupin Aug 02 '16 at 03:59
  • Sorry, I'm not sure how helper addresses relate to the DHCP server's IP address. – O_O Aug 02 '16 at 04:24
  • A helper address is the IP address of the DHCP server. Placing the `ip helper-address ` command on the VLAN interfaces enables DHCP relay and will allow DHCP to function on a VLAN on which there is no DHCP server connected. Other than that, hosts find a DHCP server via a layer-2 broadcast so the IP address doesn't really matter because the host can't contact the DHCP server via IP address since the host doesn't have an IP address. – Ron Maupin Aug 02 '16 at 14:04

2 Answers2

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If the dhcp server is running on the switch itself, then it should be visible in the running config and you can likely visually look at it.

yetdot
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I don't fully understand your question but I think I've found what you're looking for. It's called DHCP Snooping. On a switch you can configure DHCP snooping like this:

  1. Enable DHCP snooping on your switch:

Switch(config)#ip dhcp snooping

  1. Specify which VLAN DHCP snooping should be applied to:

Switch(config)#ip dhcp snooping vlan 1-3

  1. Enable DHCP snooping on the interface linked to your DHCP server:

Switch(config-if)#ip dhcp snooping trust

  1. This command will show you Mac Address, Ip Address, Lease(sec), Type, VLAN and interface of a DHCP client.

Show ip dhcp snooping binding

I hope this helped, good luck :)

Bungicasse
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