Which two statements correctly describe how IPv6 differs from IPv4? (Choose two.)

LPIC-1 Exam 102-500, objective 109. Networking fundamentals medium

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The options

Choose 2.

Correct An IPv6 address is 128 bits wide, against 32 bits for IPv4

Correct. That is the headline change: four times as many bits, written as eight groups of four hexadecimal digits rather than four decimal octets.

Correct IPv6 has no broadcast addresses; the equivalent functions use multicast

Correct. IPv6 dropped broadcast entirely. Traffic that IPv4 would broadcast is sent to well-known multicast groups such as ff02::1, all nodes on the link, and ff02::2, all routers on the link.

Not correct IPv6 keeps ARP for mapping addresses to link-layer addresses

Wrong. ARP is IPv4-only. IPv6 uses Neighbour Discovery, carried in ICMPv6 messages, and the cache is inspected with `ip -6 neigh`.

Not correct Routers along the path fragment oversized IPv6 packets on behalf of the sender

Wrong. IPv6 routers never fragment. A packet too large for the next link is dropped and an ICMPv6 Packet Too Big message goes back, leaving fragmentation to the originating host.

Not correct IPv6 requires NAT because its address space is still exhaustible in practice

Wrong. The size of the address space is precisely why IPv6 was designed for end-to-end global addressing; NAT is a workaround for IPv4 scarcity, not an IPv6 requirement.

Why

Beyond the jump from 32 to 128 bits, the differences worth remembering are structural: no broadcast, no router-side fragmentation, and ARP replaced by Neighbour Discovery over ICMPv6. Because Neighbour Discovery and Packet Too Big both ride on ICMPv6, filtering ICMPv6 as aggressively as many sites filter ICMPv4 breaks IPv6 outright. Every interface also carries a link-local fe80::/10 address in addition to any global one.

Where this comes from

Cited
manual page ipv6(7)

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