Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
What is an autonomous system in basic BGP terminology?
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
A collection of networks and routers under common administrative routing control
This is correct because that is the basic meaning of an autonomous system.
B
Distractor review
A single switch VLAN
This is wrong because a VLAN is a Layer 2 segmentation concept, not an autonomous system.
C
Distractor review
A specific OSPF area inside one router
This is wrong because an AS is not the same as an OSPF area.
D
Distractor review
A type of wireless access point
This is wrong because an AS is a routing-domain concept.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is mistaking an autonomous system for a VLAN or an OSPF area. VLANs are Layer 2 broadcast domains and do not relate to routing domains or administrative control of routing policies. Similarly, OSPF areas segment a single routing domain to optimize routing but do not represent separate administrative entities. Confusing these concepts can lead to incorrect answers because BGP’s autonomous system concept specifically refers to a collection of networks and routers under a common administrative routing policy, which is distinct from VLAN or OSPF area segmentation.
Technical deep dive
How to think about this question
An autonomous system (AS) in BGP terminology is a collection of IP networks and routers under a single administrative entity that shares a common routing policy. This concept is fundamental to BGP because it allows the protocol to manage routing between different administrative domains rather than within a single network. Each AS is assigned a unique AS number (ASN) that identifies it globally on the Internet or within private networks using BGP. BGP uses the AS concept to make routing decisions based on policies rather than just shortest path metrics. When BGP routers exchange routing information, they include the AS path attribute, which lists the AS numbers a route has traversed. This helps prevent routing loops and enforces routing policies between different autonomous systems. Cisco devices running BGP rely on this AS structure to control route advertisement and selection. A common exam trap is confusing an autonomous system with other network segmentation concepts like VLANs or OSPF areas. Unlike VLANs, which segment Layer 2 domains, or OSPF areas, which segment a single routing domain, an AS represents an entire routing domain under one administrative control. Practically, this means BGP peers are established between routers in different ASes, not within the same AS, which is a key distinction for CCNA-level understanding.
KKey Concepts to Remember
- An autonomous system groups multiple IP networks and routers under one administrative routing policy for BGP routing control.
- BGP uses autonomous system numbers (ASNs) to identify and differentiate routing domains globally or privately.
- The AS path attribute in BGP lists the sequence of autonomous systems a route has traversed to prevent routing loops.
- BGP peers establish connections between routers in different autonomous systems, not within the same AS.
- VLANs segment Layer 2 broadcast domains and do not represent autonomous systems or routing domains.
- OSPF areas segment a single routing domain internally and are not equivalent to autonomous systems.
- An autonomous system defines the boundary for routing policy enforcement in BGP inter-domain routing.
- Understanding the distinction between AS, VLAN, and OSPF area is critical to correctly answering BGP-related questions.
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?
An autonomous system groups multiple IP networks and routers under one administrative routing policy for BGP routing control.
What is the correct answer to this question?
The correct answer is: A collection of networks and routers under common administrative routing control — An autonomous system is a collection of IP networks and routers under a common routing policy or administrative control. In practical terms, it is the domain boundary concept used in BGP discussions. BGP uses AS concepts to reason about routing between separate administrative networks. This is one of the first BGP ideas learners need to understand.
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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