A network engineer is configuring a new IPv6-enabled router. They need to assign a static IPv6 address to a server. The network prefix is 2001:0db8:abcd:0012::/64. The server's MAC address is 00:0C:29:1A:2B:3C. If EUI-64 is used to generate the interface identifier, what would be the full IPv6 address?
- A2001:0db8:abcd:0012:020C:29FF:FE1A:2B3C
- B2001:0db8:abcd:0012:000C:291A:2B3C:0000
- C2001:0db8:abcd:0012:020C:291A:2B3C:0000
- D2001:0db8:abcd:0012:000C:29FF:FE1A:2B3C
Show answer & explanationAnswer & explanation
Correct answer: A. 2001:0db8:abcd:0012:020C:29FF:FE1A:2B3C
To convert a MAC address to an EUI-64 interface identifier: 1. Split the MAC address (00:0C:29:1A:2B:3C) into two 24-bit halves: 00:0C:29 and 1A:2B:3C. 2. Insert 'FF:FE' in the middle: 00:0C:29:FF:FE:1A:2B:3C. 3. Invert the 7th bit of the first octet (universal/local bit). The first octet is 00 (binary 00000000). Inverting the 7th bit (0-indexed, so the second bit from the left) changes it to 00000010, which is 02 in hex. So, 02:0C:29:FF:FE:1A:2B:3C. Combine with the prefix 2001:0db8:abcd:0012::/64 to get 2001:0db8:abcd:0012:020C:29FF:FE1A:2B3C.
Why the other options are wrong
- B. This option does not insert FF:FE and does not invert the 7th bit.
- C. This option does not insert FF:FE and does not correctly invert the 7th bit.
- D. This option inserts FF:FE but does not correctly invert the 7th bit of the first octet (00 should become 02).
IPv6 EUI-64
EUI-64 (Extended Unique Identifier-64) is a method to automatically generate a 64-bit IPv6 interface identifier from a 48-bit MAC address.
- Converts MAC address to a unique interface ID.
- Involves splitting MAC, inserting 'FFFE', and inverting the 7th bit.
- Used in Stateless Address Autoconfiguration (SLAAC).
Memory trick: EUI-64: MAC to ID, Flip Bit, FFFE In.