Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Why is a default route often called a route of last resort?
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
Best answer
Because it is used only when no more specific route matches the destination.
This is correct because the default route is a fallback path.
B
Distractor review
Because it always has the lowest bandwidth.
This is wrong because the default route is not defined by bandwidth.
C
Distractor review
Because it must be learned from OSPF only.
This is wrong because default routes can come from several sources, including static configuration.
D
Distractor review
Because it is more specific than every other route.
This is wrong because the default route is the least specific route.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is assuming the default route is learned only via OSPF or that it always has the lowest bandwidth. Candidates may also confuse the default route as being more specific than other routes. The trap lies in misunderstanding that the default route is the least specific route and serves only as a fallback when no other route matches. Misinterpreting this can lead to incorrect answers about routing behavior and protocol dependencies.
Technical deep dive
How to think about this question
A default route in IP routing is a special route used by routers to forward packets when no other more specific route matches the destination IP address. It acts as a catch-all path, directing traffic to a next-hop router or exit interface when the routing table lacks a precise match. This behavior is essential for efficient routing, especially in large or dynamic networks where maintaining exhaustive routing entries for every possible destination is impractical. Routers use a longest prefix match algorithm to determine the best route for a packet. When no route with a more specific subnet mask matches the destination, the router resorts to the default route, often represented as 0.0.0.0/0 in IPv4. This route is considered the "route of last resort" because it is only used after all other routes have been evaluated and found unsuitable. Cisco routers prefer connected and static routes with longer prefixes over the default route, ensuring that the default route is truly a fallback. A common exam trap is misunderstanding the specificity of routes. Some candidates incorrectly assume the default route is more specific or tied to certain routing protocols like OSPF. In reality, the default route is the least specific and can be configured statically or learned dynamically via multiple protocols. Practically, the default route simplifies routing tables and reduces overhead by providing a single path for unknown destinations, but it should be used carefully to avoid routing loops or blackholing traffic.
KKey Concepts to Remember
- A default route is installed in the routing table to forward packets when no more specific route matches the destination IP address.
- Routers use longest prefix match to select routes, causing the default route to be chosen only if no other route with a longer prefix exists.
- The default route is commonly represented as 0.0.0.0/0 in IPv4 routing tables and acts as a fallback path for unknown destinations.
- Cisco routers prefer connected, static, or dynamic routes with more specific prefixes over the default route during route selection.
- Default routes can be configured statically or learned dynamically via routing protocols such as OSPF, EIGRP, or RIP.
- The term 'route of last resort' emphasizes the default route’s role as the final option when no other route applies.
- Misunderstanding the default route’s specificity or protocol dependency is a common exam mistake.
- Using a default route reduces routing table size and complexity by providing a single path for all unmatched traffic.
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 default route is installed in the routing table to forward packets when no more specific route matches the destination IP address.
What is the correct answer to this question?
The correct answer is: Because it is used only when no more specific route matches the destination. — It is called a route of last resort because the router uses it only when no more specific route matches the destination. In plain language, it is the fallback path for unknown or otherwise unmatched traffic. The router still prefers connected, static, or dynamic specific routes when they exist. This term is common in routing because it captures the role of the default route exactly. The correct answer is the one centered on fallback behavior rather than speed, bandwidth, or protocol type.
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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