Notation, types, EUI-64. Relevant for CCNA, Network+.
IPv6 questions on the CCNA and Network+ are mostly about notation and recognition: can you compress an address per RFC 5952, expand one back to eight groups, tell a link-local from a unique local address, and derive an interface identifier from a MAC address.
Subbing generates addresses with realistic shapes, including runs of zero groups that tempt a wrong compression, and checks the exact RFC 5952 form. Hard rounds add prefix calculations on /56 and /60 boundaries, EUI-64 and solicited-node multicast addresses.
Generated by the same code as the app. They change with every release; the app never runs out.
IPv6 address compression: How to write an IPv6 address in its shortest valid form, the mistakes exams test for, and how to expand a compressed address back to eight groups.
Drop leading zeros in every group, replace the longest run of two or more all-zero groups with ::, and if two runs tie, compress the leftmost. Use lowercase hex.
Split the 48-bit MAC in half, insert ff:fe in the middle, and flip the seventh bit of the first byte (the universal/local bit). Prepend fe80:: for the link-local address.
fe80::/10. Unique local addresses are fc00::/7 (in practice fd00::/8), multicast is ff00::/8 and global unicast is 2000::/3.