Cisco CCNA (200-301)IP ServicesMedium
A network engineer is setting up a new DHCP server on a Cisco router. They need to ensure that the router itself does not dynamically receive an IP address from its own DHCP pool, and also that specific static IP addresses used by other critical network devices (e.g., servers) are not assigned to clients. Which DHCP configuration element should be used for these purposes?
- ADHCP relay agent
- BDHCP excluded addresses
- CDHCP lease time
- DDHCP option 150
Show answer & explanationAnswer & explanation
Correct answer: B. DHCP excluded addresses
DHCP excluded addresses are used to reserve specific IP addresses within a DHCP pool, preventing the DHCP server from assigning them to dynamic clients. This is crucial for devices requiring static IPs.
Why the other options are wrong
- A. A DHCP relay agent forwards DHCP requests between different broadcast domains, it does not reserve IP addresses.
- C. DHCP lease time defines how long a client can use an IP address before renewing it, not for reserving static IPs.
- D. DHCP option 150 is used to provide the IP address of a TFTP server for VoIP phone configuration, not for excluding addresses.
DHCP Excluded Addresses
A configuration setting on a DHCP server that specifies a range of IP addresses within a DHCP pool that should not be assigned to dynamic clients, typically reserved for static device assignments.
- Prevents conflicts with static IPs.
- Configured per DHCP pool.
- Ensures critical devices maintain their assigned addresses.
Memory trick: Exclude addresses you want to keep for special guests.