The answer is a routing loop, as the repeated debug ip packet output shows the same packet (source 10.1.1.1, destination 10.2.2.2) being received multiple times on the same interface with incrementing counters (rcvd 3, 4, 5). This pattern indicates the packet is cycling through the router without being forwarded to a new destination, a classic sign of a routing loop where the packet’s TTL is not decrementing properly or the routing table points back to the same router. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your ability to interpret debug output for loop detection, often appearing as a distractor where you must distinguish between normal retransmissions and a true loop. A common trap is assuming high packet counts always mean congestion; instead, focus on the identical source/destination and rising receive counter on the same interface. Memory tip: “Same source, same destination, same interface—think loop, not traffic.”
300-410 Network Logging and Syslog Practice Question
This 300-410 practice question tests your understanding of network logging and syslog. 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.
A network engineer runs the following command to troubleshoot a Network Logging and Syslog issue:
R1# debug ip packet
Output:
IP: s=10.1.1.1 (GigabitEthernet0/1), d=10.2.2.2, len 100, rcvd 3
IP: s=10.1.1.1 (GigabitEthernet0/1), d=10.2.2.2, len 100, rcvd 4
IP: s=10.1.1.1 (GigabitEthernet0/1), d=10.2.2.2, len 100, rcvd 5
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The router is experiencing a routing loop, as indicated by the repeated packets with the same source and destination.
The output shows repeated packets from the same source to the same destination, which may indicate a routing loop or excessive traffic. The engineer should use 'undebug all' to stop the debug and then investigate the routing table.
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.
✓
The router is experiencing a routing loop, as indicated by the repeated packets with the same source and destination.
Why this is correct
Repeated identical packets suggest a loop; debug ip packet should be used cautiously and stopped with 'undebug all'.
Related concept
Static NAT maps one inside address to one outside address.
✗
The router is functioning normally; these are just normal IP packets being forwarded.
Why it's wrong here
The high count of identical packets is abnormal and indicates a potential issue.
✗
The router is receiving multicast traffic and showing each packet individually.
Why it's wrong here
The output shows unicast IP packets, not multicast.
✗
The debug command is not working correctly because the output is too repetitive.
Why it's wrong here
The debug is functioning; repetition indicates a network issue.
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.
Trap categories for this question
Command / output trap
The output shows unicast IP packets, not multicast.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
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 300-410 NAT questions on configuration and troubleshooting.
Network Logging and Syslog — This question tests Network Logging and Syslog — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The router is experiencing a routing loop, as indicated by the repeated packets with the same source and destination. — The output shows repeated packets from the same source to the same destination, which may indicate a routing loop or excessive traffic. The engineer should use 'undebug all' to stop the debug and then investigate the routing table.
What should I do if I get this 300-410 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 300-410 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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