mediumMultiple ChoiceObjective-mapped
300-410 Practice Question: Runs the following command on Router R1: R1# show…
A network engineer runs the following command on Router R1:
R1# show crypto ipsec sa peer 10.1.1.2
interface: Tunnel0
Crypto map tag: VPN-MAP, local addr 10.1.1.1protected vrf: (none) local ident (addr/mask/prot/port): (10.1.1.0/255.255.255.0/0/0) remote ident (addr/mask/prot/port): (192.168.1.0/255.255.255.0/0/0) current_peer 10.1.1.2 port 500 PERMIT, flags={origin_is_acl,} #pkts encaps: 100, #pkts encrypt: 100, #pkts digest: 100 #pkts decaps: 0, #pkts decrypt: 0, #pkts verify: 0 #send errors 0, #recv errors 0
Based on this output, what is the problem?
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
✓
The remote peer is not sending traffic back; check routing on the remote router.
The outbound packet count (encaps) is 100, but inbound (decaps) is 0. This suggests that traffic is being sent through the tunnel but no responses are being received, possibly due to a routing issue on the remote side or a firewall blocking return traffic.
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 tunnel is working correctly; all packets are being encrypted and decrypted.
Why it's wrong here
Inbound counters are zero, indicating no decryption is happening.
- ✓
The remote peer is not sending traffic back; check routing on the remote router.
Why this is correct
Outbound packets are being sent but none received; the remote side may not have a route back or the crypto ACL is misconfigured.
- ✗
The local crypto ACL is misconfigured; it is not matching traffic.
Why it's wrong here
Outbound packets are being encapsulated, so the ACL is matching.
- ✗
The IPsec SA is not established; the tunnel is down.
Why it's wrong here
The SA is present and active; packets are being sent.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
Go deeper
Related to this question
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
Key term
MPLS Layer 3 VPN
A technology that uses Multiprotocol Label Switching to create secure, scalable virtual private networks that connect multiple sites at the network layer, where the service provider manages routing between customer sites.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 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 300-410 exam.