A router selects the best path to a destination by first comparing the Administrative Distance (AD) of all available routes. The route with the lowest AD is preferred. In Cisco IOS, a standard static route has a default AD of 1, while OSPF has a default AD of 110.

The exhibit shows that the active route to 10.10.10.0/24 is learned via OSPF (AD 110). For an OSPF route to be chosen over a configured static route to the same destination, the static route must have been configured with a custom AD value that is higher than 110, making it less preferred.

A. This is incorrect. Route selection is based on the lowest Administrative Distance, and by default, static routes (AD 1) are preferred over dynamic protocols like OSPF (AD 110).

B. The metric is only compared when two or more routes have the same Administrative Distance. Since static routes and OSPF routes have different ADs, the metric is not the primary deciding factor.

D. If the static route syntax were invalid, the command would be rejected by the router's command-line interface and the route would never be entered into the configuration.

1. Cisco Systems

Inc.

"IP Routing: Protocol-Independent Configuration Guide

Cisco IOS XE Gibraltar 16.12.x"

Route Selection in Cisco IOS. This guide states

"If multiple routes to the same destination are available

the router uses the route with the lowest administrative distance." It also lists the default AD for a static route as 1 and OSPF as 110.

2. Cisco Systems

Inc.

"IP Routing: Protocol-Independent Configuration Guide

Cisco IOS XE Gibraltar 16.12.x"

Configuring a Static Route. The documentation provides the syntax for configuring a static route

which includes an optional [distance] parameter to manually set the administrative distance: ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance]. This confirms that the AD of a static route can be modified.

3. Kurose

J. F.

& Ross

K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. Chapter 5

"The Network Layer: Control Plane

" discusses the principles of routing algorithms and path selection. It explains that routing protocols use administrative distances as a measure of trustworthiness

with lower values being preferred when multiple protocols provide a route to the same destination.