DHCP Relay Agent scenario

DHCP relay agents instead of multiple routers

What do you think is the benefit of using DHCP relay agents instead of multiple routers acting as DHCP servers?

Each router works harder to manage its DHCP addressing, in addition to the primary function of routing traffic. One DHCP server (router or computer) that is dedicated to the job is easier to manage and more centralized.

DHCP Relay Agent

Your company has two subnets on its network. Subnet A uses 192.168.1.X, subnet B uses 192.168.2.X. An Administrator installs a new server on subnet A and assigns it the address of 192.168.1.2, with a DHCP scope of 192.168.2.2–192.168.2.100. The users on subnet A complain that they cannot connect to company resources. The users on subnet B have no problems. How would you correct this problem?

• A. Add a DHCP Relay Agent
• B. Add a second DHCP Scope
• C. Add an Alias record for subnet A to the DNS server
• D. Have the users on Subnet A reboot their machines

Some types of broadcast traffic, such as DHCP messages, need to travel beyond the broadcast domain. Not all VLAN keeps its own DHCP server. A centrally managed DHCP server can provide DHCP to multiple VLANs by configuring a DHCP relay agent. A router programmed to support a relay agent receives the message and creates a message of its own to send the specified DHCP traffic beyond the broadcast domain. On some Cisco products, a more robust command, ip helper-address, can be configured to create and send helper messages to support several types of UDP traffic, including DHCP, TFTP, DNS, and NetBIOS.