Cisco CCNA Static and Dynamic Routing Questions and Answers — Questions and Answers
Question 1: A network administrator is configuring a backup route for a critical network. The primary route to the 10.10.20.0/24 network is learned via OSPF. Which command will correctly configure a static route to be used only if the OSPF route becomes unavailable?
- ip route 10.10.20.0 255.255.255.0 192.168.1.1 1
- ip route 10.10.20.0 255.255.255.0 192.168.1.1 120 (Correct answer)
- ip route 10.10.20.0 255.255.255.0 192.168.1.1 90
- ip route 10.10.20.0 255.255.255.0 192.168.1.1
Correct answer: ip route 10.10.20.0 255.255.255.0 192.168.1.1 120
This configuration creates a floating static route. The primary route is learned via OSPF, which has a default administrative distance (AD) of 110. To make the static route a backup, its AD must be higher (less preferred) than the primary route's AD. Configuring the static route with an AD of 120 makes it less preferred than the OSPF route. It will only be installed in the routing table if the OSPF route is no longer available.
Question 2: A router has the following routes in its routing table: S 192.168.32.0/26 [1/0] via 10.1.1.2 O 192.168.32.0/24 [110/2] via 10.1.1.6 R 192.168.0.0/16 [120/4] via 10.1.1.10 How will the router forward a packet destined for the IP address 192.168.32.63?
- It will use the OSPF route because it is a dynamic protocol.
- It will use the RIP route because it covers the largest address range.
- It will use the static route because it has the longest prefix match. (Correct answer)
- It will load balance across the static and OSPF routes.
Correct answer: It will use the static route because it has the longest prefix match.
The router's first criterion for selecting a path is the longest prefix match. The destination IP 192.168.32.63 falls within the range of all three routes. However, the /26 static route is the most specific (longest match) for this destination. Therefore, it will be chosen over the /24 and /16 routes, regardless of administrative distance or metric.
Question 3: Which of the following is a primary disadvantage of using static routing exclusively in a large, complex network?
- Lower security compared to dynamic routing protocols.
- Increased router CPU and memory utilization.
- Lack of automatic adaptation to network topology changes. (Correct answer)
- Consumption of network bandwidth by routing updates.
Correct answer: Lack of automatic adaptation to network topology changes.
Static routing is configured manually and does not automatically adjust to network changes, such as a link failure. In a large network, if a path goes down, traffic will be dropped until an administrator manually reconfigures the routes. Dynamic routing protocols are designed to detect such changes and automatically find a new path.
Question 4: A network administrator needs to configure a static route on a router with a multi-access exit interface, such as Ethernet. To avoid potential recursive lookups and ambiguity, the administrator wants to specify both the exit interface and the next-hop IP address. What type of static route is this?
- Recursive static route
- Directly attached static route
- Floating static route
- Fully specified static route (Correct answer)
Correct answer: Fully specified static route
A fully specified static route is one where both the exit interface and the next-hop IP address are defined in the `ip route` command. This method is recommended for multi-access interfaces like Ethernet because it eliminates the need for a recursive lookup to find the exit interface and avoids potential issues with ARP resolution that can occur with directly attached static routes on these media types.
Question 5: A Cisco router learns about the destination network 172.16.10.0/24 from two different routing sources: internal EIGRP and OSPF. Assuming default settings, which route will be installed in the routing table?
- The OSPF route, because it is an open standard.
- The EIGRP route, because it has a lower default administrative distance. (Correct answer)
- The router will install both routes and load balance the traffic.
- The OSPF route, because it has a lower metric.
Correct answer: The EIGRP route, because it has a lower default administrative distance.
When a router learns about the exact same prefix from multiple routing protocols, it uses the Administrative Distance (AD) to determine which route is more trustworthy. On Cisco routers, internal EIGRP has a default AD of 90, while OSPF has a default AD of 110. The router prefers the route with the lower AD, so the EIGRP route will be installed in the routing table.
Question 6: Which statement accurately describes a key characteristic of dynamic routing protocols like OSPF and EIGRP compared to static routing?
- They are best suited for small, simple networks with predictable traffic paths.
- They reduce administrative overhead in large networks by automatically learning routes. (Correct answer)
- They provide greater security because routes are not advertised over the network.
- They consume no router CPU or memory resources.
Correct answer: They reduce administrative overhead in large networks by automatically learning routes.
Dynamic routing protocols automatically discover remote networks and adapt to topology changes without manual intervention. This significantly reduces the administrative burden required to maintain routing tables in large or frequently changing networks, which is a major drawback of relying solely on static routes.
Cisco CCNA Static and Dynamic Routing Questions and Answers
A network administrator is configuring a backup route for a critical network.
The primary route to the 10.10.20.0/24 network is learned via OSPF.
Which command will correctly configure a static route to be used only if the OSPF route becomes unavailable?