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Difficulty: MediumIPv4 Static Routing

A network administrator is configuring an IPv4 static route on router R1 to reach the remote network 10.10.40.0/2410.10.40.0/24 across an Ethernet multiaccess segment. After issuing the command `ip route 10.10.40.0 255.255.255.0 GigabitEthernet0/0`, the administrator observes high CPU utilization and a large ARP table on R1 because the router attempts to resolve ARP for every individual destination host address in the remote network. Which command modification correctly resolves this issue while maintaining reachability?

  1. Specify the next-hop IPv4 address instead of specifying only the Ethernet exit interface.Answer
  2. B
    Append an administrative distance value of 210 to the end of the existing static route command.
  3. C
    Replace the dotted-decimal subnet mask 255.255.255.0 with the wildcard mask 0.0.0.255.
  4. D
    Configure a default static route pointing to 0.0.0.0 0.0.0.0 using interface GigabitEthernet0/0.

Answer

Specify the next-hop IPv4 address instead of specifying only the Ethernet exit interface.
When a static route on a broadcast multiaccess link (like Ethernet) points solely to an exit interface without a next-hop IP address, the router considers all host addresses in the destination subnet directly connected. Consequently, for every destination packet, the router broadcasts an ARP request on the local segment. Specifying the next-hop IPv4 address ensures the router sends packets to the specific neighbor router's MAC address, preventing ARP flooding and excessive memory usage.

Step-by-Step Solution

1
Analyze the static route syntax and multiaccess interface behavior.
Configuring `ip route` on a multiaccess Ethernet link with only an exit interface causes the router to assume the destination prefix is directly attached to that Ethernet segment.
Because Ethernet is a multiaccess medium with multiple potential devices, the router must send an ARP request for every single destination IP address in the prefix if no next-hop IP is specified.
2
Determine the solution for multiaccess static route next-hop resolution.
Including the next-hop IPv4 address (e.g., `ip route 10.10.40.0 255.255.255.0 192.168.1.2` or combining next-hop IP and exit interface) allows R1 to resolve ARP only for the next-hop router's IP address.
This avoids generating ARP requests for remote host IPs and prevents ARP table exhaustion and excessive CPU load.

Key Concept

Next-Hop IPv4 Address vs. Exit Interface in Multiaccess Static Routes
Estimated Time:1m 30s
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Topics

IPv4 Static Routing

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