CCNA IP Routing Practice Question
Why is a default route often described as a route of last resort?
⚠ Common exam trap
A frequent exam trap is assuming the default route is the most specific or fastest route, or that it is exclusively learned through OSPF. Candidates may confuse the default route with routes learned dynamically or with specific metrics. The default route is actually the least specific route, matching all destinations not covered by other entries. Misunderstanding this can lead to incorrect answers about routing behavior and protocol dependencies, especially since default routes can be configured statically or learned via multiple protocols, not just OSPF.
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
✓
Because it is used only when no more specific route matches.
It is described that way because it is used only when no more specific route matches the destination. In practical terms, the router checks for connected, static, or dynamic routes that describe the destination more precisely. If it finds none, the default route becomes the fallback path. This phrase captures the default route’s purpose exactly. It is not the fastest route or the most specific route. It is simply the catch-all route for otherwise unknown destinations.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Because it is used only when no more specific route matches.
Why this is correct
The default route, 0.0.0.0/0, matches every IP destination, but routers use longest-prefix-match forwarding. A packet is sent via the default route only when no other route in the routing table has a longer prefix length that matches the destination. Thus it acts as the final fallback, or route of last resort.
- ✗
Because it always has the lowest bandwidth.
Why it's wrong here
The classification of a route as a default route depends solely on its prefix length of /0 and destination 0.0.0.0, not on link speed or bandwidth. Even if a default route points to a low-bandwidth interface, it remains a default route; conversely, a high-bandwidth route is not a default route unless it has the /0 prefix. Therefore, bandwidth is irrelevant to the 'last resort' designation.
When this WOULD be correct
In a question asking about the characteristics of routing protocols and their performance metrics, if it specified that the default route is always chosen when bandwidth is the primary consideration, this option could be correct. For example, if the question stated that the default route is selected based on bandwidth constraints in a specific network configuration.
- ✗
Because it is more specific than any other route.
Why it's wrong here
The default route is the least specific route because its prefix length is 0, meaning it encompasses the entire IPv4 address space. Any route with a longer prefix, such as /8 or /24, is more specific and takes priority when matching a destination. So calling the default route 'more specific' directly reverses the longest-prefix-match logic that makes it a last resort.
When this WOULD be correct
In a different scenario, if the question asked about a routing protocol that uses a default route as a more specific option for certain traffic, such as a specialized routing setup in a lab environment, this option could be correct. For example, if a question stated that a specific routing protocol treats a default route as a specific route for certain traffic classes, option C could be valid.
- ✗
Because it can be learned only through OSPF.
Why it's wrong here
A default route can be configured statically or injected dynamically by multiple routing protocols, including OSPF with the default-information originate command, RIP, EIGRP, and BGP. OSPF is only one possible learning mechanism, and in many networks the default route is simply a static route to 0.0.0.0/0. Therefore, saying it can be learned only through OSPF incorrectly restricts its origins.
When this WOULD be correct
If the question asked specifically about OSPF and its ability to learn routes, a scenario could involve discussing OSPF's limitations in certain configurations where a default route is only propagated through OSPF, making this option correct in that context.
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.
✓Because it is used only when no more specific route matches.Correct answer▾
Why this is correct
The default route, 0.0.0.0/0, matches every IP destination, but routers use longest-prefix-match forwarding. A packet is sent via the default route only when no other route in the routing table has a longer prefix length that matches the destination. Thus it acts as the final fallback, or route of last resort.
✗Because it always has the lowest bandwidth.Wrong answer — click to see why▾
Why this is wrong here
The default route is not defined by bandwidth; it is a routing entry with the least specific prefix (0.0.0.0/0). Bandwidth is a metric used by routing protocols like EIGRP, but it does not determine whether a route is a default route.
★ When this WOULD be the correct answer
In a question asking about the characteristics of routing protocols and their performance metrics, if it specified that the default route is always chosen when bandwidth is the primary consideration, this option could be correct. For example, if the question stated that the default route is selected based on bandwidth constraints in a specific network configuration.
Why candidates choose this
Students may confuse the concept of 'last resort' with a route that has poor performance characteristics, such as low bandwidth, or they might mistakenly associate default routes with backup links that have lower bandwidth.
✗Because it is more specific than any other route.Wrong answer — click to see why▾
Why this is wrong here
The default route is the least specific route, matching all destinations (0.0.0.0/0). A more specific route has a longer prefix length (e.g., /24), and routers prefer more specific routes over less specific ones. Therefore, the default route is used only when no more specific match exists.
★ When this WOULD be the correct answer
In a different scenario, if the question asked about a routing protocol that uses a default route as a more specific option for certain traffic, such as a specialized routing setup in a lab environment, this option could be correct. For example, if a question stated that a specific routing protocol treats a default route as a specific route for certain traffic classes, option C could be valid.
Why candidates choose this
The phrase 'route of last resort' might be misinterpreted as 'most specific' because it is the final option, but in routing terminology, specificity refers to prefix length, not priority.
✗Because it can be learned only through OSPF.Wrong answer — click to see why▾
Why this is wrong here
A default route can be statically configured, dynamically learned via routing protocols like OSPF, EIGRP, or BGP, or even derived from DHCP. OSPF is just one of many methods to propagate a default route, not the exclusive source.
★ When this WOULD be the correct answer
If the question asked specifically about OSPF and its ability to learn routes, a scenario could involve discussing OSPF's limitations in certain configurations where a default route is only propagated through OSPF, making this option correct in that context.
Why candidates choose this
Students may recall that OSPF can generate a default route using the 'default-information originate' command, leading them to incorrectly assume that OSPF is the only way to learn a default route.
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
OSPFv3 Single-Area Configuration for IPv6
Key term
Route
A route is a path that data takes through a network from one device or network to another, determined by routing protocols and configured rules.
Key term
Router
A router is a networking device that connects different networks together and directs data traffic between them by choosing the best path for data to travel.
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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.