Examkin

Question

Difficulty: EasyDHCP Architecture and Relay Services

Client computers on a user VLAN are unable to receive dynamic IP addresses because the network's DHCP server resides on a different IP subnet across a Layer 3 boundary. Which feature must be configured on the client gateway interface to forward broadcast DHCP requests to the central DHCP server as unicast traffic?

  1. DHCP Relay AgentAnswer
  2. B
    TCP Port Forwarder on port 67
  3. C
    DNS Forwarding Service
  4. D
    Spanning Tree Protocol PortFast

Answer

DHCP Relay Agent
The correct answer identifies the DHCP Relay Agent. Because routers do not forward Layer 2 broadcast messages, a DHCP relay agent configured on the default gateway interface intercepts the local DHCP broadcast requests (UDP port 67) and forwards them as unicast packets to the central DHCP server.

Step-by-Step Solution

1
Identify the boundary restriction for DHCP broadcast messages.
Routers block Layer 2 broadcast packets (255.255.255.255) by default, preventing DHCP Discover messages from reaching remote subnets.
DHCP clients initially communicate using broadcast traffic on their local subnet.
2
Determine the required router mechanism to bridge DHCP requests across subnets.
Configuring a DHCP relay agent (e.g., `ip helper-address`) transforms client broadcast requests into unicast IP packets directed to the DHCP server address.
Unicast packets can be routed across Layer 3 networks to reach a central DHCP server.

Key Concept

DHCP Relay Agent functionality across Layer 3 boundaries
Estimated Time:45s
Rate this question

Topics

DHCP Architecture and Relay Services

More questions from this topic