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CCDE 400-007: Which type of IPv6 can be used for addressing design?

By: Author Alex Lim

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Question

Company XYZ has a new network based on IPv6. Some of the subnets that they are planning to use will be confidential and need an addressing scheme that confines them to the local campus network. Which type of IPv6 addresses can be used for these networks in the IPv6 addressing design?

A. link-local addresses
B. private addresses
C. unique local addresses
D. local addresses

Answer

C. unique local addresses

Explanation

The correct answer to the question is C. unique local addresses.

When designing an IPv6 addressing scheme for confidential subnets that are limited to the local campus network, the appropriate type of IPv6 addresses to use is unique local addresses (ULAs). Here’s a comprehensive explanation:

  1. Link-local addresses (A): Link-local addresses are automatically assigned to interfaces on a specific link or network segment. They are primarily used for local communication and are not routable beyond the link. While link-local addresses are suitable for communication within a single subnet or network segment, they are not appropriate for confining subnets to a specific local campus network as they cannot be used for routing beyond the link.
  2. Private addresses (B): Private addresses, also known as Unique Local IPv6 Unicast Addresses (ULA), are reserved for private use within an organization or site. They are similar to private IPv4 addresses (such as those in the 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16 ranges). Private IPv6 addresses have the prefix fc00::/7, which provides a large address space for private use. Private addresses are not globally routable, meaning they are confined to the local network and are not advertised on the public internet. Therefore, they are suitable for addressing confidential subnets within a local campus network.
  3. Unique local addresses (C): Unique local addresses (ULA) are a type of private IPv6 addresses specifically designed for local use within an organization or site. They have the prefix fc00::/7 and are divided into two parts: the FC00::/8 prefix for locally assigned addresses (also known as “randomly generated”) and the FD00::/8 prefix for site-specific addresses (also known as “manually assigned”). Unique local addresses are intended to be used for internal networks and are not globally routable. They provide the advantage of uniqueness within the local network while still confining the addressing scheme to the local campus network, making them suitable for addressing confidential subnets.
  4. Local addresses (D): There is no specific “local address” type in the context of IPv6 addressing. Local addresses may refer to link-local addresses (A), but as mentioned earlier, they are limited to communication within a single link and cannot be used for confining subnets to a specific local campus network.

In summary, when designing an IPv6 addressing scheme for confidential subnets confined to the local campus network, the appropriate type of addresses to use is unique local addresses (ULAs). ULAs are private addresses that are not globally routable and provide uniqueness within the local network, making them suitable for addressing confidential subnets.

Reference

Cisco Certified Design Expert CCDE v3.0 400-007 certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the Cisco Certified Design Expert CCDE v3.0 400-007 exam and earn Cisco Certified Design Expert CCDE v3.0 400-007 certification.