CCNA Network Services and Security Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0

  Why it's wrong here

  Configuring a static default route with only an exit interface (e.g., ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0) can work, but on multiaccess Ethernet it is less ideal. Without a next-hop IP, the router assumes every destination is directly connected and will broadcast ARP requests for each remote destination, which creates excessive ARP traffic and often requires the provider to run proxy ARP. Using the provider's next-hop IP avoids these issues by specifying the exact gateway and allowing normal ARP resolution only for that gateway.

  When this WOULD be correct

  In a different scenario where a router has multiple WAN links and the question asks for a static route to be configured for a specific interface, option A could be correct if the interface is indeed the exit point for traffic. For example, if the question specifies routing traffic out of a specific GigabitEthernet interface without a defined next-hop IP.

• ✓

  ip route 0.0.0.0 0.0.0.0 198.51.100.1

  Why this is correct

  This command installs a default route (0.0.0.0/0) with a next-hop IP of 198.51.100.1. On an Ethernet multiaccess link, specifying the next-hop address is preferable because the router will ARP for that specific gateway and use the resolved MAC as the frame destination, while also tracking reachability via ARP. This approach avoids relying solely on the interface being up and works cleanly on provider Ethernet handoffs, where the next-hop is a known device.

• ✗

  ip route 255.255.255.255 255.255.255.255 198.51.100.1

  Why it's wrong here

  This command creates a host route for the single address 255.255.255.255, not a default route. A default route must have a prefix of 0.0.0.0 with a mask of 0.0.0.0 so it matches all destinations. Furthermore, pointing a host route at a next hop of itself (198.51.100.1) is nonsensical and would only affect traffic destined to that exact address, leaving all other traffic without a path.

  When this WOULD be correct

  In a scenario where a router needs to direct traffic specifically to a single host IP address (e.g., a management server) rather than a default route, the command 'ip route 255.255.255.255 255.255.255.255 198.51.100.1' would be appropriate for routing traffic intended only for that host.

• ✗

  No static default route should ever be used on Ethernet.

  Why it's wrong here

  Static default routes are perfectly valid and commonly used on Ethernet WAN links, such as carrier Ethernet or MPLS handoffs, so the claim that they should never be used is incorrect. The issue is not the medium but how the route is specified; using a next-hop IP is standard and works well. Overbroad prohibitions like this ignore that many networks rely on static defaults for simple and predictable egress routing.

  When this WOULD be correct

  In a scenario where the question specifies that a router is connected to multiple WAN links, and the requirement is to ensure no static routes are used for redundancy or load balancing, option D could be correct. This would imply that dynamic routing protocols are preferred for managing multiple paths.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.

Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”