The correct conclusion is that this tunnel is used for PIM register encapsulation to the RP. The output from show ip pim tunnel reveals a PIM Encap type tunnel with source 10.0.0.7 and destination 10.0.0.8, and the status is up, which specifically indicates that Router R7 is encapsulating multicast data into register messages destined for the rendezvous point at 10.0.0.8. This is a fundamental concept in PIM sparse mode, where a first-hop router uses a tunnel interface to send unicast-encapsulated register packets to the RP until the shared tree is established. On the ENCOR 350-401 exam, this command tests your ability to differentiate between PIM encapsulation (source to RP) and decapsulation (RP to source), a common trap where candidates confuse the tunnel direction. A reliable memory tip is to associate “Encap” with “outbound to the RP” — think of the source router wrapping the data like a package and sending it to the destination RP address.
350-401 IP Multicast Practice Question
This 350-401 practice question tests your understanding of ip multicast. 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.
A network engineer issues the following command on Router R7:
R7# show ip pim tunnel
Tunnel1:
Type: PIM Encap
Source: 10.0.0.7, Destination: 10.0.0.8
Status: up
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
This tunnel is used for PIM register encapsulation to the RP.
The 'show ip pim tunnel' output shows a PIM encapsulation tunnel (Tunnel1) with source 10.0.0.7 and destination 10.0.0.8, and the status is up. This type of tunnel is used for PIM register encapsulation when a source sends to an RP. The correct answer is that this tunnel is used for sending register messages to the RP.
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.
✓
This tunnel is used for PIM register encapsulation to the RP.
Why this is correct
PIM Encap tunnels are used to encapsulate multicast packets from the first-hop router to the RP.
Related concept
Static NAT maps one inside address to one outside address.
✗
This tunnel is used for MDT data group forwarding.
Why it's wrong here
MDT tunnels are used in MVPN, not for PIM register.
✗
This tunnel is used for BSR messages.
Why it's wrong here
BSR messages are not encapsulated in tunnels.
✗
This tunnel is used for Auto-RP announcements.
Why it's wrong here
Auto-RP uses multicast, not tunnels.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 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 350-401 NAT questions on configuration and troubleshooting.
IP Multicast — This question tests IP Multicast — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: This tunnel is used for PIM register encapsulation to the RP. — The 'show ip pim tunnel' output shows a PIM encapsulation tunnel (Tunnel1) with source 10.0.0.7 and destination 10.0.0.8, and the status is up. This type of tunnel is used for PIM register encapsulation when a source sends to an RP. The correct answer is that this tunnel is used for sending register messages to the RP.
What should I do if I get this 350-401 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 350-401 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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Question Discussion
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