Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
What is the main reason a default route is sometimes 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
It is used only when no more specific route matches the destination
This is correct because the default route acts as the fallback when the table lacks a better match.
B
Distractor review
It always has the highest bandwidth link
This is wrong because route selection is not based on the phrase “last resort” meaning highest bandwidth.
C
Distractor review
It is processed before all connected routes
This is wrong because connected and other more specific routes are preferred over the default route.
D
Distractor review
It disables all dynamic routing protocols
This is wrong because default routes can coexist with dynamic routing protocols.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is assuming the default route is processed before connected or static routes or that it disables dynamic routing protocols. Some candidates mistakenly believe the default route has the highest priority or bandwidth, leading to incorrect answers. The default route is actually the least specific and is only used when no other route matches. Misunderstanding this can cause confusion about routing behavior and route selection in Cisco devices, especially under exam conditions where precise knowledge of routing order is critical.
Technical deep dive
How to think about this question
A default route in IP routing is a special type of route that matches any destination IP address not explicitly listed in the routing table. It acts as a catch-all or fallback path, guiding packets toward a next-hop router when no more specific route exists. This mechanism is crucial in simplifying routing tables, especially in edge routers or branch offices where maintaining full routing information is impractical. Routers use a longest prefix match algorithm to select the best route for forwarding packets. When no route matches the destination IP address with a more specific prefix, the router resorts to the default route, often represented as 0.0.0.0/0 in IPv4. This behavior makes the default route the "route of last resort" because it is only used after all other possible routes have been evaluated and found unsuitable. Cisco routers prioritize routes based on prefix length and administrative distance, ensuring the default route is the least preferred unless no other options exist. A common exam trap is misunderstanding the role of the default route as being processed before other routes or associating it with bandwidth or dynamic routing protocol behavior. In practice, the default route coexists with dynamic routing protocols like OSPF or EIGRP and is only selected when no other route matches. This ensures efficient routing and prevents unnecessary traffic blackholing. In real-world networks, default routes are vital for directing unknown traffic toward upstream providers or core routers, simplifying network design and reducing routing overhead.
KKey Concepts to Remember
- A default route matches all destination IP addresses not found in the routing table, acting as a fallback path for unknown destinations.
- Routers use the longest prefix match rule to select routes, preferring more specific routes over the default route with prefix 0.0.0.0/0.
- The default route is called the route of last resort because it is only used when no other more specific route exists.
- Cisco routers compare administrative distance and prefix length to determine route preference, ensuring default routes are least preferred.
- Default routes coexist with dynamic routing protocols such as OSPF and EIGRP and do not disable them.
- The default route does not imply higher bandwidth or faster links; route selection is based on specificity and administrative distance.
- Using a default route simplifies routing tables on edge or branch routers by reducing the need for full routing information.
- The route of last resort concept prevents routing loops and blackholing by providing a controlled fallback path for unknown destinations.
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 matches all destination IP addresses not found in the routing table, acting as a fallback path for unknown destinations.
What is the correct answer to this question?
The correct answer is: It is used only when no more specific route matches the destination — A default route is called the 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 instruction the router follows when it does not have a better answer in the routing table. That makes it extremely useful for branch routers, Internet edge devices, and other places where unknown destinations should simply be sent to an upstream path. The default route is not “last” because it is slow or because it is dangerous. It is last because it is the least specific match. As soon as the router finds a more specific prefix, that route takes precedence. This is a core route-selection concept and helps explain why default routes work so well alongside more detailed routing information.
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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