Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
What is the main reason route administrative distance exists in Cisco routing logic?
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
To rank the trustworthiness of different route sources
This is correct because administrative distance helps the router choose between routes learned from different sources.
B
Distractor review
To identify the MAC address of the next hop
This is wrong because administrative distance is unrelated to MAC resolution.
C
Distractor review
To determine trunk native VLAN behavior
This is wrong because administrative distance has nothing to do with VLAN trunking.
D
Distractor review
To encrypt routing updates between routers
This is wrong because administrative distance is a route preference value, not encryption.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mistaking administrative distance for routing metrics or other unrelated functions like MAC address resolution or VLAN behavior. Some candidates incorrectly believe administrative distance affects how routers identify next-hop MAC addresses or manage VLAN trunks, which is false. Administrative distance strictly ranks the trustworthiness of route sources, not path cost or hardware addressing. Confusing AD with encryption of routing updates is another trap; AD does not provide security but only route preference. Recognizing that AD is a cross-protocol route selection tool helps avoid these common misconceptions.
Technical deep dive
How to think about this question
Administrative distance (AD) is a Cisco-specific value assigned to routes learned from different routing sources to indicate their trustworthiness. It is a numeric value ranging from 0 to 255, where a lower AD means a more trusted route source. For example, directly connected interfaces have an AD of 0, static routes default to 1, and dynamic routing protocols like OSPF and EIGRP have higher AD values. This mechanism allows a router to compare routes from multiple sources and select the best one to install in its routing table. When a router receives multiple routes to the same destination network from different routing protocols or sources, it uses administrative distance to decide which route to prefer. The route with the lowest AD is chosen and installed in the routing table, while others are ignored. This decision process is independent of the routing metric used within a protocol; AD is a cross-protocol preference tool. For example, if a static route and an OSPF route exist for the same destination, the router will prefer the static route because its AD (1) is lower than OSPF’s default AD (110). A common exam trap is confusing administrative distance with routing metrics. Metrics are used to select the best path within a single routing protocol, such as OSPF cost or EIGRP composite metric, whereas administrative distance compares routes from different protocols or sources. Understanding this distinction is critical because administrative distance determines which routing protocol’s route is installed, while metrics determine the best path inside that protocol. Practically, network engineers use AD to influence route selection when multiple routing protocols coexist, such as preferring static routes over dynamic ones for critical paths.
KKey Concepts to Remember
- Administrative distance assigns a numeric trustworthiness value to routes learned from different routing sources to aid route selection.
- Routers compare administrative distance values when multiple routes to the same destination exist from different protocols or sources.
- The route with the lowest administrative distance is installed in the routing table, overriding routes with higher values.
- Administrative distance is distinct from routing metrics, which compare path costs within a single routing protocol.
- Directly connected interfaces have the lowest administrative distance of 0, making them the most trusted route source.
- Static routes have a default administrative distance of 1, typically preferred over dynamic routing protocols like OSPF or EIGRP.
- Administrative distance does not affect MAC address resolution, VLAN trunking behavior, or encryption of routing updates.
- Understanding administrative distance helps network engineers control route preference when multiple routing protocols coexist.
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 assigns a numeric trustworthiness value to routes learned from different routing sources to aid route selection.
What is the correct answer to this question?
The correct answer is: To rank the trustworthiness of different route sources — Administrative distance exists so the router can rank the trustworthiness of different route sources. In plain language, if the router learns the same destination from multiple sources such as static routing and OSPF, it needs a way to decide which source to trust more before installing the route. This is different from a metric, which usually compares paths inside one routing protocol. Administrative distance is a cross-source preference tool.
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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