Question 1mediummatching
Full question →Match each routing term to its most accurate meaning.
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mediummatchingObjective-mapped
Match each routing term to its most accurate meaning.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mixing up administrative distance and metric, assuming they both compare path cost. Administrative distance actually compares the reliability of routing sources, not the quality of paths within a protocol. Another trap is thinking longest-prefix match chooses the best path based on cost or trust, when it strictly selects the most specific route mask. Misunderstanding default routes as primary routes rather than fallback options also leads to errors. These confusions cause candidates to incorrectly identify how routers prioritize routes in Cisco devices.
Technical deep dive
How to think about this question
Routing decisions in Cisco routers rely on multiple concepts to determine the best path for forwarding packets. Administrative distance (AD) is a value assigned to each routing protocol or source to indicate its trustworthiness; lower AD values are preferred. For example, directly connected routes have an AD of 0, static routes 1, EIGRP 90, OSPF 110, and RIP 120. When multiple routing protocols provide routes to the same destination, the router selects the route with the lowest AD. Within a single routing protocol, the router uses metrics to compare multiple candidate routes. Metrics are protocol-specific values that quantify path cost, such as bandwidth, delay, hop count, or composite calculations. The router chooses the route with the lowest metric as the best path. Once the best route is selected, the router uses the longest-prefix match rule to forward packets. This rule means the router looks for the route with the most specific subnet mask matching the destination IP address. For example, a route to 192.168.1.0/24 is more specific than 192.168.0.0/16, so packets destined for 192.168.1.x will use the /24 route. If no specific route matches, the router uses a default route (0.0.0.0/0) if configured, which acts as a fallback path for all unmatched destinations. This mechanism ensures efficient and predictable routing behavior. A common exam trap is confusing administrative distance with metric or misunderstanding the role of longest-prefix match. Administrative distance compares trustworthiness between different routing sources, not path cost. Metrics compare paths within the same routing protocol. Longest-prefix match is about route specificity, not trust or cost. Misapplying these concepts can lead to incorrect answers about route selection. In practical networks, understanding these distinctions helps troubleshoot routing issues and optimize path selection, especially in multi-protocol environments or when default routes are involved.
KKey Concepts to Remember
- Administrative distance determines the trustworthiness of a routing source by assigning a numeric value, with lower values preferred when multiple routing protocols provide routes to the same destination.
- Routing metrics quantify the cost of a path within a routing protocol, allowing the router to select the best route among multiple candidates from the same protocol.
- Longest-prefix match selects the most specific route in the routing table by choosing the route with the most bits matching the destination IP address.
- A default route acts as a catch-all path used when no other more specific route exists in the routing table for a given destination.
- Routers use administrative distance first to choose between routes from different routing protocols before considering metrics within a single protocol.
- Metrics vary by routing protocol; for example, OSPF uses cost based on bandwidth, while EIGRP uses a composite metric including bandwidth and delay.
- Longest-prefix match is fundamental to IP routing and ensures packets are forwarded using the most precise route available, improving routing efficiency.
- Default routes simplify routing tables by providing a fallback path, especially useful in stub networks or when routing to 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?
Administrative distance determines the trustworthiness of a routing source by assigning a numeric value, with lower values preferred when multiple routing protocols provide routes to the same destination.
What exam trap should I watch out for?
Common exam trap: answer the scenario, not the keyword: A frequent exam trap is mixing up administrative distance and metric, assuming they both compare path cost. Administrative distance actually compares the reliability of routing sources, not the quality of paths within a protocol. Another trap is thinking longest-prefix match chooses the best path based on cost or trust, when it strictly selects the most specific route mask. Misunderstanding default routes as primary routes rather than fallback options also leads to errors. These confusions cause candidates to incorrectly identify how routers prioritize routes in Cisco devices.
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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