CCNA IP Routing Practice Question
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
R3 has the static route 'ip route 172.20.8.0 255.255.255.0 192.168.1.1'. Packets destined for 172.20.8.0/24 are being dropped. What is the most likely cause?
⚠ Common exam trap
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.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
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.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The destination network mask should be /16 instead of /24
Why it's wrong here
Changing the destination network mask from /24 to /16 would not correct the issue. The exhibit explicitly shows a /24 static route, and the mask defines the intended destination prefix; however, the fundamental problem is that the next-hop is unreachable. Even with a /16 mask, the route would still be unusable because the next-hop remains unresolved.
When this WOULD be correct
In a different scenario where a static route is configured for a subnet that should indeed be larger, such as 172.20.0.0/16, a candidate might be asked to identify if the subnet mask is incorrectly set, making /16 the correct choice for proper routing.
- ✓
The next-hop address is not reachable from R3
Why this is correct
The static route is invalid because R3 cannot resolve the specified next-hop address. A static route with a next-hop IP requires that the next-hop be reachable via a directly connected network or another valid route in the routing table; otherwise, the route is not installed. Since the next-hop is unreachable, packets cannot be forwarded and the route remains inactive.
- ✗
Static routes require an outbound access list
Why it's wrong here
Static routes do not require an outbound access control list (ACL) to function. ACLs are used to filter traffic passing through or destined to the router, but they have no bearing on whether a static route is installed or usable. The route here fails because of a reachability problem, not because of any missing traffic filter.
When this WOULD be correct
In a different question, if the context specifies that a static route is being used in a network where security policies are enforced through access lists, and the question asks about the configuration of static routes under such constraints, then this option could be correct.
- ✗
The route must use administrative distance 255
Why it's wrong here
An administrative distance of 255 marks the route as untrusted and effectively disables it from being installed in the routing table. Routes with AD 255 are considered unreachable and are not used for forwarding; they are typically reserved for default-information or special cases. Setting AD to 255 would make the route even less usable, so it cannot be the required fix.
When this WOULD be correct
In a different question setup where a static route is configured with an administrative distance of 255, the question might ask why the route is not being used. In that case, the correct answer would be that the route is effectively disabled due to the administrative distance being set to 255.
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.
✓The next-hop address is not reachable from R3Correct answer▾
Why this is correct
The static route is invalid because R3 cannot resolve the specified next-hop address. A static route with a next-hop IP requires that the next-hop be reachable via a directly connected network or another valid route in the routing table; otherwise, the route is not installed. Since the next-hop is unreachable, packets cannot be forwarded and the route remains inactive.
✗The destination network mask should be /16 instead of /24Wrong answer — click to see why▾
Why this is wrong here
The destination network mask of /24 is correct for the subnet 172.20.8.0/24, and changing it to /16 would incorrectly encompass a larger range of addresses, which is not relevant to the issue of dropped packets.
★ When this WOULD be the correct answer
In a different scenario where a static route is configured for a subnet that should indeed be larger, such as 172.20.0.0/16, a candidate might be asked to identify if the subnet mask is incorrectly set, making /16 the correct choice for proper routing.
Why candidates choose this
Candidates may confuse subnetting concepts and assume that a larger subnet mask would resolve routing issues, leading them to incorrectly believe that adjusting the mask would fix the packet drop problem.
✗Static routes require an outbound access listWrong answer — click to see why▾
Why this is wrong here
Static routes do not inherently require an outbound access list; they can function without one. The issue in this scenario is related to the reachability of the next-hop address, not access lists.
★ When this WOULD be the correct answer
In a different question, if the context specifies that a static route is being used in a network where security policies are enforced through access lists, and the question asks about the configuration of static routes under such constraints, then this option could be correct.
Why candidates choose this
Candidates may confuse static routes with dynamic routing protocols, which often utilize access lists for filtering. This misunderstanding can lead them to incorrectly believe that access lists are a requirement for static routes.
✗The route must use administrative distance 255Wrong answer — click to see why▾
Why this is wrong here
This option is wrong because administrative distance 255 means the route is unreachable, which would not be a plausible configuration for a static route intended to be used. In this scenario, the static route is not the issue; rather, the next-hop address is unreachable.
★ When this WOULD be the correct answer
In a different question setup where a static route is configured with an administrative distance of 255, the question might ask why the route is not being used. In that case, the correct answer would be that the route is effectively disabled due to the administrative distance being set to 255.
Why candidates choose this
Candidates may find this option tempting because they might confuse administrative distance settings with route reachability, thinking that a high administrative distance could be a reason for packet drops.
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?”
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
Interpreting HSRP and VRRP Operational Status
Key term
Next hop
A next hop is the next immediate router or device that a packet is sent to on its path from source to destination.
Key term
Static route
A static route is a manually configured path in a router's routing table that tells the router exactly where to send packets for a specific destination network.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.