200-301 · Question #1457
Refer to the exhibit. The IPv6 address for the LAN segment on router R1 must be configured using the EUI-64 format. When configured which ipv6 address is produced by the router?
The correct answer is D. 2001:db8:3bb8:3bb1:C801:B3FF:FEB8:1. The IPv6 address produced by EUI-64 format combines the given network prefix with a 64-bit interface identifier derived from the router's MAC address by inserting 'FFFE' and inverting the 7th bit of the MAC's first octet.
Question
Refer to the exhibit. The IPv6 address for the LAN segment on router R1 must be configured using the EUI-64 format. When configured which ipv6 address is produced by the router?
Exhibits
Options
- A2001:db8:3bb8:3bb1:C810:B3FF:FF8B:1
- B2001:db8:3bb8:3bb1:C001:3BFE:FF81:1
- C2001:db8:3bb8:3bb4:6363:93FF:EF66:1
- D2001:db8:3bb8:3bb1:C801:B3FF:FEB8:1
How the community answered
(33 responses)- A6% (2)
- B3% (1)
- C15% (5)
- D76% (25)
Why each option
The IPv6 address produced by EUI-64 format combines the given network prefix with a 64-bit interface identifier derived from the router's MAC address by inserting 'FFFE' and inverting the 7th bit of the MAC's first octet.
This address does not correctly apply the EUI-64 conversion rules, either in the `FF:FE` insertion or the bit inversion from any plausible MAC address.
This address does not correctly apply the EUI-64 conversion rules, as the `FF:FE` is not in the correct position relative to the MAC address segments or the bit inversion is incorrect.
This address has a different prefix and an interface ID that does not conform to the EUI-64 derivation from a standard MAC address format.
Assuming the router's MAC address in the exhibit was `88:01:B3:B8:00:01` and the prefix was `2001:db8:3bb8:3bb1::/64`, the EUI-64 process would take the MAC address, insert `FF:FE` in the middle to become `88:01:B3:FF:FE:B8:00:01`, and then invert the 7th bit of the first octet (`88` becomes `C8`), resulting in the interface ID `C801:B3FF:FEB8:1`.
Concept tested: IPv6 EUI-64 address generation
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/configuration/xe-16/ipv6-xe-16-book/ip6-eui64.html
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