Courseiva
← 200-301
Full test
Question 399 of 1,052
hardmultiple choiceObjective-mapped

CCNA Practice Question: Notices that hosts on VLAN 100 (192.168.10.0/24)…

This 200-301 practice question tests your understanding of 200-301 exam topics. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Exhibit

R1# show ip route 10.0.0.1
% Network not in table

R1# show ip route 10.0.0.0
Routing entry for 10.0.0.0/24
  Known via "eigrp", distance 90, metric 30720, type internal
  Redistributing via eigrp 1
  Last update from 192.168.1.2 on GigabitEthernet0/0, 00:12:34 ago
  Routing Descriptor Blocks:
  * 192.168.1.2, from 192.168.1.2, 00:12:34 ago, via GigabitEthernet0/0
      Route metric is 30720, traffic share count is 1

R1# show ip route 10.0.0.0 255.255.255.0
Routing entry for 10.0.0.0/24
  Known via "connected", distance 0, metric 0 (connected)
  Redistributing via eigrp 1
  Directly connected via GigabitEthernet0/1

R1# show ip route 10.0.0.1 255.255.255.255
% Network not in table

A network engineer notices that hosts on VLAN 100 (192.168.10.0/24) cannot ping the loopback interface (10.0.0.1/32) of a directly connected router R2. The engineer checks R1's routing table and sees an entry for 10.0.0.0/24 via a different next-hop, but no entry for 10.0.0.1/32. What is the most likely reason for the connectivity failure?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "most likely"

    Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice
Full question →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

R2 is advertising the loopback as a /24 network, not a /32 host route.

The routing table shows a /24 route for 10.0.0.0 via EIGRP (next-hop 192.168.1.2) and a directly connected /24 route for 10.0.0.0. However, the specific /32 loopback address 10.0.0.1 is not in the table. Since the longest-prefix match rule applies, the router needs a /32 route to reach the loopback. The absence of this route indicates that R2 is not advertising the loopback as a /32, or R1 does not have a route to it. The most likely cause is that R2's loopback interface is configured with a /24 mask instead of /32, causing R2 to advertise a /24 route, which R1 installs but does not provide a match for the /32 destination.

Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✗

    The loopback interface on R2 is administratively down.

    Why it's wrong here

    If the interface were down, R2 would not advertise any route for 10.0.0.0/24, but R1 shows a /24 route via EIGRP, so the interface is up.

  • ✓

    R2 is advertising the loopback as a /24 network, not a /32 host route.

    Why this is correct

    The loopback address 10.0.0.1/32 is typically advertised as a /32. If R2's loopback is configured with a /24 mask, it advertises 10.0.0.0/24. R1 then has a /24 route but no /32 route, so when trying to reach 10.0.0.1, the longest-prefix match fails, and the router drops the packet.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    Access ports place end devices into a single VLAN.

  • ✗

    R1 has a route for 10.0.0.0/24 via a different next-hop, causing a routing loop.

    Why it's wrong here

    While R1 has two routes for 10.0.0.0/24 (one connected, one via EIGRP), the connected route is more specific (directly connected) but still a /24. The issue is not a loop but the lack of a /32 route.

  • ✗

    The EIGRP metric for the /24 route is too high, so R1 prefers the connected route.

    Why it's wrong here

    The EIGRP metric is 30720, which is normal, and the connected route has a lower administrative distance (0 vs 90), so R1 uses the connected route for 10.0.0.0/24. However, neither route is a /32, so the problem remains.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.

✓R2 is advertising the loopback as a /24 network, not a /32 host route.Correct answer▾

Why this is correct

The loopback address 10.0.0.1/32 is typically advertised as a /32. If R2's loopback is configured with a /24 mask, it advertises 10.0.0.0/24. R1 then has a /24 route but no /32 route, so when trying to reach 10.0.0.1, the longest-prefix match fails, and the router drops the packet.

✗The loopback interface on R2 is administratively down.Wrong answer — click to see why▾

Why this is wrong here

The presence of the /24 route indicates the interface is up and being advertised.

✗R1 has a route for 10.0.0.0/24 via a different next-hop, causing a routing loop.Wrong answer — click to see why▾

Why this is wrong here

The routing table shows both routes, but the problem is the missing /32 entry, not a loop.

✗The EIGRP metric for the /24 route is too high, so R1 prefers the connected route.Wrong answer — click to see why▾

Why this is wrong here

The metric and AD are not the issue; the lack of a /32 route is.

Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: an active trunk can still block the VLAN you need

A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.

Trap categories for this question

  • Command / output trap

    If the interface were down, R2 would not advertise any route for 10.0.0.0/24, but R1 shows a /24 route via EIGRP, so the interface is up.

Detailed technical explanation

How to think about this question

VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.

KKey Concepts to Remember

  • Access ports place end devices into a single VLAN.
  • Trunk ports carry multiple VLANs between switches.
  • Allowed VLAN lists decide which VLANs can cross a trunk.
  • Native VLAN mismatch can create confusing symptoms.

TExam Day Tips

  • Use show vlan brief to verify access VLANs.
  • Use show interfaces trunk to verify trunk state and allowed VLANs.
  • Do not treat every same-VLAN issue as a routing problem.

Key takeaway

A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

Real-world example

How this comes up in practice

A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.

What to study next

Got this wrong? Here's your next step.

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.

Related practice questions

Related 200-301 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

CCNA subnetting practice questions

Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.

CCNA OSPF practice questions

Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.

CCNA VLAN practice questions

Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.

CCNA STP practice questions

Practise spanning tree, root bridge election, port roles and STP troubleshooting.

CCNA EtherChannel practice questions

Practise LACP, PAgP, port-channel behaviour and bundle requirements.

CCNA ACL practice questions

Practise standard and extended ACLs, permit/deny logic and traffic filtering.

CCNA NAT practice questions

Practise static NAT, dynamic NAT, PAT and inside/outside address translation.

CCNA DHCP practice questions

Practise DHCP scopes, relay, leases and troubleshooting.

CCNA show ip route practice questions

Practise routing-table output, longest-prefix match, AD and route selection.

CCNA show interfaces trunk practice questions

Practise trunk verification and VLAN forwarding across switches.

CCNA wireless security practice questions

Practise WLAN security, authentication and wireless architecture concepts.

CCNA IPv6 practice questions

Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.

Practice this exam

Start a free 200-301 practice session

Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.

10 questions20 questions30 questions50 questionsTimed 30
200-301 practice-test guide →Study guide →Browse all practice tests

FAQ

Questions learners often ask

What does this 200-301 question test?

Access ports place end devices into a single VLAN.

What is the correct answer to this question?

The correct answer is: R2 is advertising the loopback as a /24 network, not a /32 host route. — The routing table shows a /24 route for 10.0.0.0 via EIGRP (next-hop 192.168.1.2) and a directly connected /24 route for 10.0.0.0. However, the specific /32 loopback address 10.0.0.1 is not in the table. Since the longest-prefix match rule applies, the router needs a /32 route to reach the loopback. The absence of this route indicates that R2 is not advertising the loopback as a /32, or R1 does not have a route to it. The most likely cause is that R2's loopback interface is configured with a /24 mask instead of /32, causing R2 to advertise a /24 route, which R1 installs but does not provide a match for the /32 destination.

What should I do if I get this 200-301 question wrong?

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 200-301 questions on switching, trunking, and access-port configuration.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Access ports place end devices into a single VLAN.

About these practice questions

Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →

How Courseiva writes practice questions · Editorial policy

Keep practising

More 200-301 practice questions

Browse all 200-301 questions →

Question Discussion

Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.

Loading comments…

Sign in to join the discussion.

This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.