200-301 - Network Fundamentals - Section 1.6

Configure and verify IPv4 addressing and subnetting, configure IPv6 addressing and prefixes, and describe IPv6 address types including unicast, anycast, multicast, and modified EUI-64.

Apply variable-length subnet masking to divide an IPv4 block into the required number of subnets and hosts, deriving network address, broadcast address, and usable host range from a prefix length. Compress and expand IPv6 addresses, identify global unicast, unique local, and link-local scopes, and derive an interface ID using modified EUI-64. Recognise the need for private RFC 1918 addressing and where NAT bridges it to public space.

IPv4 subnettingVLSMPrivate addressing (RFC 1918)IPv6 address typesModified EUI-64

Practice question for this objective

Free sampleNetwork Fundamentalshard

An engineer is auditing a list of IPv6 addresses assigned across a campus and must flag those that are globally routable unicast addresses, meaning they fall within the 2000::/3 range reserved for global unicast. Which two addresses qualify? Select TWO.

  • A2001:db8:acad:10::1, configured statically on a server interface for external reachability Correct
  • Bfe80::21a:2bff:fe3c:4d5e, formed automatically on the interface at boot time
  • C2400:cb00:2049:1::a29f:1804, allocated from a provider block for internet hosts Correct
  • Dff02::1, used to reach every node listening on the local link segment
  • Efd00:1234:5678:9abc::1, generated locally for traffic that stays inside the site
Recognise that IPv6 global unicast addresses occupy the 2000::/3 block, distinct from link-local, unique local, and multicast ranges. Global unicast addresses are drawn from 2000::/3, so their first hextet starts with 2 or 3; this is what makes them routable across the public internet. Link-local (fe80::/10), unique local (fc00::/7), and multicast (ff00::/8) all sit outside that block and serve segment-local, site-local, or group-delivery roles instead, so they are excluded.

Why A is correct: Its leading bits place it inside 2000::/3, the block defined for global unicast, so it is a globally routable unicast address.

Why B is wrong: An address beginning fe80 sits in fe80::/10 and is link-local only, valid on a single segment and never routed globally, so it is not global unicast.

Why C is correct: It begins with 2400, which lies within 2000::/3, marking it a global unicast address suitable for routing across the internet.

Why D is wrong: Any address starting ff00::/8, including ff02::1, is multicast rather than unicast, so it identifies a group of receivers and cannot be a global unicast address.

Why E is wrong: The fd prefix falls in fc00::/7, the unique local range that is private to a site and not advertised on the internet, so it is not global unicast.

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