Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Exhibit
ip route 172.20.8.0 255.255.255.0 10.1.13.2 show ip route 10.1.13.0 % Network not in table
Exhibit: R3 has the static route shown below, but packets to 172.20.8.0/24 are being dropped. What is the most likely cause?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
The destination network mask should be /16 instead of /24
The problem shown is next-hop reachability, not the destination mask.
B
Best answer
The next-hop address is not reachable from R3
If the next hop cannot be resolved, the static route cannot work.
C
Distractor review
Static routes require an outbound access list
They do not.
D
Distractor review
The route must use administrative distance 255
That would make it unusable.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is assuming that an incorrect subnet mask on the static route causes packets to be dropped. While subnet masks affect routing accuracy, they do not cause next-hop reachability failures. Another trap is believing that static routes require outbound ACLs, which is false; ACLs control traffic filtering but do not impact static route functionality. Additionally, some may think setting the administrative distance to 255 is necessary for static routes, but this actually disables the route, making it unusable. The key mistake is overlooking the requirement that the next-hop IP address must be reachable for the static route to work, which is the actual cause of packet drops in this scenario.
Technical deep dive
How to think about this question
Static routing is a fundamental routing method where network administrators manually configure routes to specific destination networks. Each static route includes a destination network and a next-hop IP address or exit interface. The router uses this information to forward packets destined for the specified network. However, for the static route to be effective, the next-hop IP address must be reachable, meaning the router must have a valid route to that next-hop address in its routing table. Without this, the static route is considered invalid and will not be installed. When a router processes a static route, it first checks if the next-hop IP address is reachable either through a directly connected interface or via another routing protocol. If the next-hop is unreachable, the router discards packets destined for the static route’s network because it cannot forward them properly. This behavior ensures that routers do not forward packets into a black hole. The subnet mask in the static route must correctly represent the destination network, but an incorrect mask typically results in routing mismatches rather than next-hop reachability issues. A common exam trap is confusing subnet mask errors or administrative distance settings with next-hop reachability problems. For example, setting an administrative distance to 255 disables the route, but this is unrelated to next-hop reachability. Similarly, static routes do not require outbound ACLs to function, so assuming ACLs are necessary is incorrect. Practically, network engineers verify next-hop reachability by pinging the next-hop IP and checking the routing table to ensure the next-hop is accessible before relying on static routes for forwarding traffic.
KKey Concepts to Remember
- A static route requires the next-hop IP address to be reachable in the routing table for the route to be installed and used for forwarding packets.
- If the next-hop address in a static route is not reachable, the router will not install the static route in its routing table, causing packets to be dropped.
- The subnet mask in a static route must correctly match the intended destination network to ensure proper routing, but incorrect masks do not cause next-hop reachability failures.
- Administrative distance determines route preference but setting it to 255 makes the route unusable, so static routes typically use a default AD of 1.
- Static routes do not require outbound access control lists (ACLs) to function; ACLs are used separately for traffic filtering and security.
- Routers forward packets based on the routing table entries, and if a static route’s next-hop is unreachable, the router cannot forward packets to that destination network.
- Next-hop reachability depends on the router having a valid route to the next-hop IP address, either directly connected or learned via another routing protocol.
- Troubleshooting static routes often involves verifying the next-hop IP address reachability using commands like 'ping' and checking the routing table for connected or learned routes.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
A static route requires the next-hop IP address to be reachable in the routing table for the route to be installed and used for forwarding packets.
What is the correct answer to this question?
The correct answer is: The next-hop address is not reachable from R3 — A static route can only work if the next-hop address is reachable. If the next hop is down or missing from the routing table, the route cannot forward traffic successfully.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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