Which two statements about IPv4 and IPv6 networks are true? (Choose two.)

In IPv6, routers do not perform fragmentation; instead, if a packet is too large for a link, the router discards it and sends an ICMPv6 "Packet Too Big" message, prompting the source host to fragment the packet if necessary.

Although IPv6 headers do not include a checksum, UDP, as a transport layer protocol, still uses an optional checksum to verify data integrity in both IPv4 and IPv6, becoming mandatory for UDP over IPv6 when IPv6 headers lack a network layer checksum.

In IPv6, routers do not perform fragmentation; they drop oversized packets and send an ICMPv6 "Packet Too Big" message back to the sender.

In IPv4, fragmentation can be performed by both the source host and intermediate routers if the packet exceeds the MTU of a link.

The IPv4 header itself includes a checksum, and the transport layer (TCP/UDP) also optionally or mandatorily uses checksums for end-to-end integrity; this statement is not broadly true for IPv4's network layer.

IPv6 headers specifically do not include a checksum at the network layer, relying on link-layer and transport-layer checksums for integrity.