Question 1hardmultiple choice
Full question →- → Why each wrong option is wrong in this specific scenario
- → When each wrong option would be correct
- → Real-world analogy and exam trap analysis
- → Related glossary terms and similar practice questions
Question 617 of 1,052
hardmultiple choiceObjective-mapped
CCNA Practice Question: An engineer is deploying a new Cisco Catalyst…
This 200-301 practice question tests your understanding of 200-301 exam topics. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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
Switch# show interfaces gigabitethernet1/0/1
GigabitEthernet1/0/1 is up, line protocol is up
Hardware is Gigabit Ethernet, address is aaaa.bbbb.cccc (bia aaaa.bbbb.cccc)
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is 1000BaseLX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 1000 bits/sec, 2 packets/sec
5 minute output rate 1000 bits/sec, 2 packets/sec
1234 packets input, 150000 bytes, 0 no buffer
Received 100 broadcasts (0 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
567 packets output, 100000 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped outAn engineer is deploying a new Cisco Catalyst 9300 switch in a campus wiring closet. The uplink to the distribution switch uses a 1000BASE-LX SFP module. After connecting the fiber, the interface shows 'up/up' but the engineer notices that the 'input errors' counter is incrementing rapidly. There are no CRC errors, but many 'runts' and 'giants' are reported. What is the most likely cause of these input errors?
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.
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
✓
Check the fiber distance and ensure it is within the 5 km limit for 1000BASE-LX; if over, use a single-mode fiber extender.
The 'show interfaces' output shows zero input errors and no runts or giants, indicating that the interface is operating correctly. However, the scenario describes incrementing runts and giants, which are typically caused by a speed or duplex mismatch. Since both ends are set to 1000 Mbps full-duplex, the mismatch is not speed or duplex. The 1000BASE-LX SFP has a maximum distance of 5 km over single-mode fiber, but the engineer may be using multimode fiber (which has a shorter distance limit of 550 m for 1000BASE-SX), causing signal degradation and errors. The correct answer is to verify the fiber type and distance.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replace the SFP with a 1000BASE-SX module.
Why it's wrong here
1000BASE-SX is for multimode fiber and shorter distances (up to 550 m). If the fiber is single-mode, this would not work and could cause errors.
- ✓
Check the fiber distance and ensure it is within the 5 km limit for 1000BASE-LX; if over, use a single-mode fiber extender.
Why this is correct
The 1000BASE-LX SFP supports up to 5 km over single-mode fiber. If the distance exceeds this, signal attenuation causes errors. A fiber extender or different optics would be needed.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
Configure the interface with 'speed 100' and 'duplex full' to match the SFP capabilities.
Why it's wrong here
The 1000BASE-LX SFP only supports 1000 Mbps; forcing 100 Mbps would cause the interface to go down or have errors.
- ✗
Replace the fiber patch cable with a CAT6a copper cable and use a 1000BASE-T SFP.
Why it's wrong here
Changing to copper would require different SFPs and cabling, but the issue is distance on fiber, not the media type.
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.
✓Check the fiber distance and ensure it is within the 5 km limit for 1000BASE-LX; if over, use a single-mode fiber extender.Correct answer▾
Why this is correct
The 1000BASE-LX SFP supports up to 5 km over single-mode fiber. If the distance exceeds this, signal attenuation causes errors. A fiber extender or different optics would be needed.
✗Replace the SFP with a 1000BASE-SX module.Wrong answer — click to see why▾
Why this is wrong here
The scenario does not indicate the fiber type; using SX might not solve the issue if the fiber is single-mode.
✗Configure the interface with 'speed 100' and 'duplex full' to match the SFP capabilities.Wrong answer — click to see why▾
Why this is wrong here
Gigabit SFPs cannot operate at 100 Mbps; this would break connectivity.
✗Replace the fiber patch cable with a CAT6a copper cable and use a 1000BASE-T SFP.Wrong answer — click to see why▾
Why this is wrong here
This does not address the root cause of distance-related errors on fiber.
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: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-301 NAT questions on configuration and troubleshooting.
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.
FAQ
Questions learners often ask
What does this 200-301 question test?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: Check the fiber distance and ensure it is within the 5 km limit for 1000BASE-LX; if over, use a single-mode fiber extender. — The 'show interfaces' output shows zero input errors and no runts or giants, indicating that the interface is operating correctly. However, the scenario describes incrementing runts and giants, which are typically caused by a speed or duplex mismatch. Since both ends are set to 1000 Mbps full-duplex, the mismatch is not speed or duplex. The 1000BASE-LX SFP has a maximum distance of 5 km over single-mode fiber, but the engineer may be using multimode fiber (which has a shorter distance limit of 550 m for 1000BASE-SX), causing signal degradation and errors. The correct answer is to verify the fiber type and distance.
What should I do if I get this 200-301 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 200-301 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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 →
Keep practising
More 200-301 practice questions
- A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that w…
- A switch has DHCP snooping enabled, but users still experience IP-to-MAC spoofing attacks. Which additional feature shou…
- Switch SW1 sends traffic for VLAN 30 across a trunk to SW2, but hosts in VLAN 30 on SW2 cannot communicate with hosts in…
- What problem is HSRP designed to solve?
- Which DHCP message does the client send to formally accept an offered address?
- What metric does RIP use to choose the best path?
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.