Cisco Certified Network Associate (CCNA) Practice Exam

What is the default behavior of a router when it receives a DHCP request from a PC?

1. Drop the request

2. Broadcast the request to all switches

3. Forward the request to the designated server

4. Drop the request and log the incident

The correct answer is: Drop the request

When a router receives a DHCP request from a PC, the default behavior is not to drop the request. Normally, DHCP requests are broadcast messages sent by the PC to discover available DHCP servers on the network. The router's role in this situation involves forwarding DHCP broadcasts from clients to the server if configured properly to do so, particularly in larger networks where DHCP servers might reside on different subnets. The correct behavior generally involves forwarding the DHCP request if the network is set up to allow it. If no DHCP server is configured, the router may not process the request beyond dropping it, but the default expectation is that the router should allow DHCP traffic to be forwarded to the designated server. In environments where routers are correctly configured for DHCP relay (using the IP helper-address command on Cisco routers), they will facilitate the forwarding of DHCP discovery packets to the appropriate server, allowing clients to receive IP addresses and configuration settings.