mediumMultiple Choice
300-410 Practice Question: Examine the following partial configuration on…
Examine the following partial configuration on Router R1: ```
interface Tunnel0
ipv6 address 2001:DB8:1::1/64 tunnel source GigabitEthernet0/0 tunnel destination 2001:DB8:2::2 tunnel mode ipv6ip ``` What is the effect of this configuration?
⚠ Common exam trap
Cisco often tests the distinction between tunnel transport and passenger protocols, trapping candidates who confuse the tunnel destination address family with the tunnel mode requirements.
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 tunnel will not come up because the tunnel destination is an IPv6 address instead of an IPv4 address.
The tunnel mode ipv6ip requires an IPv4 address as the tunnel destination because it encapsulates IPv6 packets inside IPv4 packets for transport over an IPv4 network. In this configuration, the tunnel destination is set to an IPv6 address (2001:DB8:2::2), which is invalid for this tunnel mode, preventing the tunnel interface from coming up.
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 will successfully encapsulate IPv6 packets in IPv4 and forward them.
Why it's wrong here
The tunnel destination is configured as an IPv6 address, but `tunnel mode ipv6ip` requires an IPv4 destination for encapsulation. IPv6-in-IPv4 tunnels carry IPv6 traffic across an IPv4-only transit network, so the destination must be an IPv4 address. This mode would be correct when connecting IPv6 islands through IPv4 infrastructure.
- ✓
The tunnel will not come up because the tunnel destination is an IPv6 address instead of an IPv4 address.
Why this is correct
With `tunnel mode ipv6ip`, the outer transport header is IPv4, so the tunnel source and destination must both be IPv4 addresses. Specifying an IPv6 destination (2001:DB8:2::2) violates this requirement, preventing the tunnel interface from reaching an up state.
- ✗
The tunnel will use IPv6 as the transport protocol, encapsulating IPv4 packets.
Why it's wrong here
The `tunnel mode ipv6ip` keyword sets an IPv4 transport carrying IPv6 payloads, so the tunnel source and destination must be IPv4 addresses; here they are IPv6, which fails. It is tempting because IPv6-over-IPv4 tunnels are common for connecting IPv6 islands across an existing IPv4 core.
- ✗
The configuration is correct for a 6to4 tunnel.
Why it's wrong here
The `tunnel mode ipv6ip` keyword specifies a manual IPv6-in-IPv4 tunnel, not 6to4, which requires `tunnel mode ipv6ip 6to4` plus an IPv4 address embedded in the 2002::/16 prefix. 6to4 is tempting because it also carries IPv6 over IPv4, and would be correct for automatic, prefix-derived tunnelling between 6to4 sites.
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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.