CCST IPv4 vs. IPv6 Addressing 2 — Questions and Answers
Question 1: How many bits are in an IPv6 address compared to an IPv4 address?
- IPv6: 64 bits, IPv4: 32 bits
- IPv6: 128 bits, IPv4: 32 bits (Correct answer)
- IPv6: 256 bits, IPv4: 64 bits
- IPv6: 128 bits, IPv4: 64 bits
Correct answer: IPv6: 128 bits, IPv4: 32 bits
IPv6 is 128 bits (eight groups of hex digits); IPv4 is 32 bits (dotted decimal), providing vastly larger address space.
IPv4: ~4.3 billion addresses (2^32). IPv6: ~3.4 x 10^38 addresses (2^128). The massive space eliminates the need for NAT and enables true end-to-end connectivity.
Question 2: Which transition mechanism encapsulates IPv6 packets within IPv4 packets?
- NAT64
- Tunneling (Correct answer)
- Dual stack
- DNS64
Correct answer: Tunneling
Tunneling wraps IPv6 packets inside IPv4 packets for transport across IPv4-only infrastructure.
Types include 6to4 (automatic, 2002::/16), ISATAP (intranets), Teredo (NAT traversal via UDP), and GRE (manual point-to-point). Adds overhead but is practical during transition.
Question 3: What type of IPv6 address begins with fe80::/10 and is used for single-segment communication?
- Global unicast
- Link-local (Correct answer)
- Multicast
- Anycast
Correct answer: Link-local
Link-local addresses (fe80::/10) are auto-assigned and limited to the local network segment, not routable beyond it.
Every IPv6 interface auto-generates a link-local address. They enable NDP operations and DHCPv6 communication. Unlike IPv4's APIPA, link-local in IPv6 is normal and essential.
Question 4: Which protocol replaced ARP in IPv6 for address resolution?
- DHCPv6
- NDP (Neighbor Discovery Protocol) (Correct answer)
- ICMPv4
- IGMP
Correct answer: NDP (Neighbor Discovery Protocol)
IPv6 uses NDP with ICMPv6 Neighbor Solicitation/Advertisement messages instead of ARP broadcasts.
NDP (RFC 4861) handles address resolution via multicast NS/NA messages, plus Router Discovery, Prefix Discovery, and Duplicate Address Detection. Can be secured with SEND.
Question 5: What advantage does IPv6 provide regarding IPsec support?
- IPv6 does not support IPsec
- IPsec is a mandatory part of the IPv6 specification while optional in IPv4 (Correct answer)
- IPv6 uses different encryption than IPsec
- No difference between IPv4 and IPv6
Correct answer: IPsec is a mandatory part of the IPv6 specification while optional in IPv4
IPsec was built into the IPv6 specification from the beginning, while it is optional for IPv4.
IPv6's Extension Header mechanism provides cleaner IPsec integration. All compliant implementations support it, enabling end-to-end encryption without NAT complications.
Question 6: How does SLAAC in IPv6 differ from DHCP in IPv4?
- SLAAC requires a central server
- SLAAC allows devices to self-configure addresses using router-advertised prefixes without a central server (Correct answer)
- SLAAC only works on wireless
- No functional difference
Correct answer: SLAAC allows devices to self-configure addresses using router-advertised prefixes without a central server
SLAAC lets devices auto-configure by combining router-advertised prefixes with self-generated interface IDs, no DHCP server needed.
Process: generate link-local, send Router Solicitation, receive Router Advertisement with prefix, combine prefix with self-generated interface ID. Stateless DHCPv6 can supplement SLAAC for DNS info.
CCST IPv4 vs. IPv6 Addressing 2
How many bits are in an IPv6 address compared to an IPv4 address?