Even if you don’t use a Nagios monitoring server, you can grep the check_dhcp binary or compile it from source and use the check to test a DHCP-Server. E.g. ./check_dhcp -v -s <dhcp_server_address> -r <expected_ip_address> -m <mac_address_touse>
One simple method is to simply run a sniffer like tcpdump/wireshark on a computer and send out a DHCP request. If you see any offers other then from your real DHCP server then you know you have a problem.
I’m assuming a basic knowledge of what DHCP does and how to configure your DHCP server of choice in this answer, but before we talk about multiple DHCP servers on the same network, let’s first of all quickly re-cap how clients receive IP addresses from DHCP at the most basic level. DHCP on a simple … Read more