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Difficulty: MediumIPv6 Addressing and Deployment

A network systems engineer is designing an IPv6 addressing scheme for an internal enterprise network containing multiple subnets connected via internal routers. The design requirement dictates that internal systems must be routable across all corporate locations without being globally reachable on the public Internet. Which of the following IPv6 address types should be assigned to these hosts?

  1. Unique Local addresses starting within the fd00::/8 prefix blockAnswer
  2. B
    Link-Local addresses starting within the fe80::/10 prefix block
  3. C
    Global Unicast addresses starting within the 2000::/3 prefix block
  4. D
    Multicast addresses starting within the ff02::/16 prefix block

Answer

Unique Local addresses starting within the fd00::/8 prefix block should be assigned.
Unique Local Addresses (ULA) using the fd00::/8 block (within fc00::/7) are designed specifically for internal site communication across routed networks. They permit multi-subnet internal routing while remaining non-routable on the public IPv6 Internet.

Step-by-Step Solution

1
Analyze the routability and accessibility requirements for the network scenario
Internal devices must communicate across routed subnets internally, but must remain unreachable from the public IPv6 Internet.
This requirement calls for an internally routable, non-globally scoped IPv6 unicast prefix.
2
Evaluate the candidate IPv6 address scopes against the criteria
Unique Local Addresses (ULA, prefix fc00::/7, commonly fd00::/8) serve as the IPv6 equivalent of IPv4 private addresses (RFC 1918). They route freely across internal routers while ISP routers discard them by default.
Link-Local addresses cannot cross routers, and Global Unicast addresses are publicly routable.

Key Concept

IPv6 Unique Local Address Scope & Deployment
Estimated Time:1m 0s
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Topics

IPv6 Addressing and Deployment

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