Which statement describes fragmentation behavior in IPv6?

• A. Fragmentation is performed by routers along the path
• B. Fragmentation is not supported in IPv6
• C. Fragmentation is performed by the destination host
• D. Fragmentation is performed by the sender using extension headers

Answer: (D)

Fragmentation in IPv6 is performed by the sending host using a Fragment extension header. IPv6 routers do not fragment packets along the path; if a packet is too large to forward, the router drops it and sends back an ICMPv6 Packet Too Big message, guiding Path MTU Discovery. When fragmentation is needed, the originating host splits the payload into appropriately sized fragments and attaches a Fragment header to each piece. This header includes the fragment offset, an identification value to match all fragments of the same packet, and a flag indicating whether more fragments follow. The destination host then reassembles the fragments into the original packet before delivering it to the upper-layer protocol. This arrangement shifts fragmentation responsibility to the source and keeps router processing simpler.