Exam 200-301 topic 1 question 52 discussion

B is correct! Overlay tunneling encapsulates IPv6 packets in IPv4 packets for delivery across an IPv4 infrastructure (a core network or the figure below). By using overlay tunnels, you can communicate with isolated IPv6 networks without upgrading the IPv4 infrastructure between them. Overlay tunnels can be configured between border devices or between a border device and a host; however, both tunnel endpoints must support both the IPv4 and IPv6 protocol stacks. IPv6 supports the following types of overlay tunneling mechanisms: 1 Manual 2 Generic routing encapsulation (GRE) 3 IPv4-compatible 4 6to4 5 Intrasite Automatic Tunnel Addressing Protocol (ISATAP)

B. 6 to 4 tunneling Imagine you have two groups of friends, one group that talks using a secret code with letters and numbers (IPv6), and another group that talks using regular words (IPv4). But you want these two groups to talk to each other, even though they use different ways of talking. Now, think of a big tunnel that connects these two groups. When someone from the first group wants to send a message to someone in the second group, they put their message in a special envelope and send it through the tunnel. When the message comes out of the tunnel on the other side, it looks like a message from the second group, even though it started with the first group's way of talking. In the same way, 6 to 4 tunneling helps the two different ways of talking, IPv6 and IPv4, to understand each other. It wraps the IPv6 message in an IPv4 wrapper and sends it through a tunnel. This way, they can communicate even though they use different codes.

Ref: IPv6 Tunnel through an IPv4 Network – Cisco “… Introduction … Overlay tunneling encapsulates IPv6 packets in IPv4 packets for delivery across an IPv4 infrastructure. …” A. NAT Wrong answer. B. 6 to 4 tunneling Correct answer. C. L2TPv3 Wrong answer. D. dual-stack Wrong answer.

B. 6 to 4 tunneling is correct

6 to 4 tunnel

An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4 network to remote IPv6 networks https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/configuration/xe-3s/ir-xe-3s-book/ip6-6to4-tunls-xe.pdf

B is the correct answer... 6 to 4 https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/configuration/15-mt/ir-15-mt-book/ip6-ipoverip6-tunls.html#:~:text=Generic%20routing%20encapsulation%20(GRE)%20IPv4,%2Dto%2Dpoint%20encapsulation%20scheme.