How to block issuing a dhcp ip to a perticular host

Can you setup a static reservation based on mac, and then give it a non-valid IP? I don't know of any way to do it other than. Technically any port in xyz should be able to issue a dhcp request and get an IP, so you can't block by port or access-list, and you can't disable the ip-helper or this would break everything. Therefore, your only course of action is on the dhcp service itself, and by MAC- address which is the only thing the originating station uses to identify itself for static entries.

Why not commit the server to a specific port associated with VLAN abc, and specify the MAC address of the server with the port security command?

e.g.: interface FastEthernet0/3 description Server switchport access vlan switchport mode access switchport nonegotiate switchport port-security switchport port-security violation restrict switchport port-security mac-address aaaa.bbbb.cccc

If the MAC of the server is associated with a specific port, which is associated with a specific VLAN (abc), would that not prevent the server from accessing the DHCP server via any other port, including VLAN xyz ports?

Best Regards, News Reader

Agreed on this solution. I didn't think it would be an option else keeping the server on the same port/vlan would work fine without the mac security, but this would solve the problem.