Cisco CCNA (200-301)IP ConnectivityMedium
Refer to the following router output: ``` R1# show ip route Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP a - application route + - replicated route, % - next hop override, p - overrides from PfR Gateway of last resort is 10.0.0.1 to network 0.0.0.0 S* 0.0.0.0/0 [1/0] via 10.0.0.1 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.0.0.0/24 is directly connected, GigabitEthernet0/0 L 10.0.0.2/32 is directly connected, GigabitEthernet0/0 ``` Based on the output, what is the administrative distance of the default route configured on R1?
- A1
- B0
- C10.0.0.1
- D110
Show answer & explanationAnswer & explanation
Correct answer: A. 1
The administrative distance is the first number in the brackets `[AD/Metric]` of a routing table entry. For the default route `S* 0.0.0.0/0 [1/0] via 10.0.0.1`, the administrative distance is `1`. The `S` code indicates it's a static route, which by default has an administrative distance of 1.
Why the other options are wrong
- B. 0 is the AD for directly connected routes, not static routes.
- C. 10.0.0.1 is the next-hop IP address, not the administrative distance.
- D. 110 is the administrative distance for OSPF internal routes, not static routes.
Static Route Administrative Distance
By default, static routes have an administrative distance of 1, indicating a high level of trustworthiness compared to dynamic routing protocols.
- Administrative distance (AD) is used to select the best path when multiple routing protocols provide routes to the same destination.
- Lower AD is preferred.
- AD 1 is the default for static routes.
- AD 0 is for directly connected routes.
Memory trick: AD is the judge, lower number wins the knowledge.