There are multiple DHCP servers that run on our LAN, and some of them are unwanted. Can I configure my OS to reject certain responses so that I can get the correct one?

1 Answer 1


Unfortunately that's the wrong way to achieve this. DHCP is a protocol that works completly in broadcast. From the discovery, to the offer, to the request and the acknowledge; every single step happens over the broadcast address

The DHCP server normally uses option 54 to identify himself (See RFC2132, Chapter 9.7). If you have a rouge DHCP server in your net, nothing stops him from identifying himself as your DHCP server with that option 54.

So, you can configure your client system to ignore other DHCP servers, but as you see that's only an ineffective solution.

If someone stuck a "rogue DHCP server" in your network, then you need to find out how/why and take necessary measures to ensure it doesn't happen again. Such a problem should be solved at layer 1 or 2, if possible.

One solution is called DHCP snooping. This is a mechanism where your switches are configured to determine where DHCP messages are allowed to come from. Your switches must support that.

Another solution is using VLANs. In a company for example, you can put every department or every floor in a separate VLAN. If now there is a rouge DHCP server only that VLAN is affected and you can encircle the rouge device very fast. Switches must of course support VLANs.


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