DHCP helper-address and pool

[aweise]

I would think the answer to this is pretty simple, but I can't confirm.

At one of our remote locations, we have a layer 3 switch (Cisco 3850) that has a DHCP pool configured for our IP phones. However, on the VLAN interface for the phone VLAN, we also have a helper-address configured. Configurations are below:

ip dhcp pool VOIP
 network 10.1.26.0 255.255.255.0
 default-router 10.1.26.1

interface Vlan500
 ip address 10.1.26.1 255.255.255.0
 ip helper-address 192.168.10.10
 ip helper-address 192.168.20.10

If the helper address is configured on the SVI, does the local pool on the switch simply override the helper-address? The pool on the switch is responding to the queries and successfully handing out the IP address leases.

[BradEast1]

Not certain that one negates the other. My logic would be that it's faster to get a response from the local DHCP pool rather than convert the request to unicast, forward to your remote DHCP server and receive a response. Thus, the local pool would win.

[Yachay · Accepted solution]

The only information I found is this: https://supportforums.cisco.com/t5/lan-switching-and-routing/dhcp-local-pool-dhcp-helper-address/td-p/2909743

Hope this helps.

[aweise]

Yachay, thank you for that link. My guess is what BradEast1 said in that the switch would respond more quickly than the remote DHCP server.