200-301 · Question #522
Refer to the exhibit. An engineer is configuring the HO router. Which IPv6 address configuration must be applied to the router fa0/1 interface for the router to assign a unique 64-brt IPv6 address to
The correct answer is A. ipv6 address 2001:DB8:0:1:C601:42FF:FE0F:7/64. To assign a unique 64-bit IPv6 address using EUI-64, the router's MAC address is extended with FFFE and a specific bit in the first byte is inverted.
Question
Refer to the exhibit. An engineer is configuring the HO router. Which IPv6 address configuration must be applied to the router fa0/1 interface for the router to assign a unique 64-brt IPv6 address to Itself?
Exhibits
Options
- Aipv6 address 2001:DB8:0:1:C601:42FF:FE0F:7/64
- Bipv6 address 2001:DB8:0:1:C601:42FE:800F:7/64
- Cipv6 address 2001:DB8:0:1:FFFF:C601:420F:7/64
- Dipv6 address 2001:DB8:0:1:FE80:C601:420F:7/64
How the community answered
(43 responses)- A44% (19)
- B30% (13)
- C9% (4)
- D16% (7)
Why each option
To assign a unique 64-bit IPv6 address using EUI-64, the router's MAC address is extended with FFFE and a specific bit in the first byte is inverted.
The EUI-64 process takes the 48-bit MAC address `C401.420F.0007` and inserts `FFFE` in the middle to form `C4:01:42:FF:FE:0F:00:07`. The 7th bit (0-indexed from left, bit 6) of the first byte (`C4`, which is `11000100` in binary) is then inverted (the `0` becomes `1`), resulting in `11000110` (`C6` in hex), yielding the interface ID `C601:42FF:FE0F:7` combined with the given prefix.
This option contains an incorrect interface identifier, as it does not correctly apply the EUI-64 bit inversion rule to the MAC address's first octet.
Concept tested: IPv6 EUI-64 address generation
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/configuration/xe-3s/ipv6-xe-3s-book/ip6-eui64.html
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