Stumped on Configuring the DHCP Relay Agent — Check Out These Tips!
Author’s Note: For this blog, the DHCP Relay Agent is configured on a virtual machine, running Windows Server 2012 R2, where Routing and Remote Access Service (RRAS) is installed through Server Manager. This virtual machine acts as the router that connects multiple networks.
A DHCP Relay Agent transmits messages between clients and DHCP servers in different networks. This eliminates having to install and configure a DHCP server in every network, saving time and resources.
For the second project in Tech Jobs Academy, one of the objectives was to “configure the DHCP Relay Agent on the VLAN without the DHCP server.” Sounds simple and straightforward enough. Well, not quite. I ran into a few kinks while following setup guides that I found online. However, I figured out a few components that should be checked out to ensure that the DHCP Relay Agent runs smoothly in a network infrastructure.
The Ping Test
Never underestimate the power of ping; it is a very basic, but useful command in Command Prompt that tests whether the source computer can communicate with a specific computer. Upon setting up all my virtual machines, I had to first confirm that my DHCP server actually worked in distributing IPv4 addresses. That way, when I ping my DHCP server from a computer in another network and this computer is unable to receive an IPv4 address, I would know that the problem is most likely in the DHCP Relay Agent.
In the image above, the first ping to a computer in the local network yielded a reply. Don’t let that fool you though! You’ll notice that the reply contains IPv6 addresses, which raises a red flag since my network environment is designed to resolve IPv4 addresses. The main item to examine is the Network Connections — verify that the source computer is joined to the domain and that all the domain controllers and servers have the appropriate subnet mask, default gateway and DNS server address.
If that does not solve the problem, check the host records to determine if there are any conflicting information that might hinder communications between computers.
Check Your DHCP Relay Agent Properties
Did you input the DHCP server address in DHCP Relay Agent Properties box? In my case, this crucial information somehow got deleted during unknown background computer activities. I racked my brains thinking that there was a deeper reason as to why my virtual machines could not communicate across networks, but I guess not. After I entered the DHCP server address, my client machine in the second network was finally able to pick up an IPv4 address from the DHCP server in the first network.
…And this is how I successfully configured the DHCP Relay Agent!
