200-301 · Question #1113
Refer to the exhibit. Which format matches the Modified EUI-64 IPv6 interface address for the network 2001:db8::/64?
The correct answer is D. 2001:db8::5200:00ff:fe04:0000/64. Modified EUI-64 generates an IPv6 interface identifier by transforming a MAC address into a 64-bit value, which includes inserting FFFE and inverting the 7th bit of the first MAC address byte.
Question
Refer to the exhibit. Which format matches the Modified EUI-64 IPv6 interface address for the network 2001:db8::/64?
Exhibits
Options
- A2001:db8::5000:00ff:fe04:0000/64
- B2001:db8::4332:5800:41ff:fe06:/64
- C2001:db8::5000:0004:5678:0090/64
- D2001:db8::5200:00ff:fe04:0000/64
How the community answered
(28 responses)- A7% (2)
- B18% (5)
- C4% (1)
- D71% (20)
Why each option
Modified EUI-64 generates an IPv6 interface identifier by transforming a MAC address into a 64-bit value, which includes inserting FFFE and inverting the 7th bit of the first MAC address byte.
This option fails to correctly invert the 7th bit of the MAC address's first byte, retaining '50' instead of changing it to '52'.
This option's interface identifier does not follow the correct Modified EUI-64 conversion rules from the given MAC address.
This option does not include the mandatory 'FFFE' segment in the middle of the interface identifier as required by the EUI-64 format.
The MAC address 5000.0004.0000 is split as 5000.00 and 04.0000, then FFFE is inserted to get 5000:00FF:FE04:0000. Inverting the 7th bit of the first byte (50h or 01010000b) changes it to 52h (01010010b), resulting in the interface identifier 5200:00FF:FE04:0000. Combined with the prefix 2001:db8::/64, the full address is 2001:db8::5200:00ff:fe04:0000/64.
Concept tested: IPv6 Modified EUI-64 address generation
Source: https://www.cisco.com/c/en/us/td/docs/ios/ipv6/configuration/guide/ipv6_address_config_c_ipv6-address-cfg-book/ipv6_address_config_c_ipv6-address-cfg-book_chapter_010.html
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