200-301 · Question #1500
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 B. 2001:db8:1a44:41a4:C801:BEFF:FE4A:1. The EUI-64 process generates an IPv6 interface identifier by taking a 48-bit MAC address, inserting 'FFFE' in the middle, and inverting the 7th bit of the first byte.
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:db8:1a44:41a4:C081:BFFF:FE4A:1
- B2001:db8:1a44:41a4:C801:BEFF:FE4A:1
- C2001:db8:1a44:41a4:4660:592F:FE65:1
- D2001:db8:1a44:41a4:C800:BAFE:FF00:1
How the community answered
(45 responses)- A13% (6)
- B78% (35)
- C7% (3)
- D2% (1)
Why each option
The EUI-64 process generates an IPv6 interface identifier by taking a 48-bit MAC address, inserting 'FFFE' in the middle, and inverting the 7th bit of the first byte.
This option does not correctly apply the EUI-64 conversion rules regarding the 7th bit inversion or the structure of FFFE insertion based on a typical MAC address.
For EUI-64, if the original MAC address is 88:01:BE:4A:00:01 (assuming this from the exhibit), it's split, FFFE is inserted in the middle, resulting in 8801:BEFF:FE4A:0001. The 7th bit of the first byte '88' (binary 10001000, 7th bit is 0) is then inverted to 'C8' (binary 11001000), producing C801:BEFF:FE4A:0001 as the interface ID, which appended to the given prefix 2001:db8:1a44:41a4: forms the complete IPv6 address.
This option's interface identifier (4660:592F:FE65:1) deviates significantly from the EUI-64 rules, failing to incorporate 'FFFE' correctly or reflect the original MAC address segments.
This option's interface identifier (C800:BAFE:FF00:1) incorrectly inserts 'BAFE' and 'FF00' instead of the standard 'FFFE' in the middle of the MAC address to form the EUI-64 identifier.
Concept tested: IPv6 EUI-64 address generation
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_ipv6/configuration/15-s/ipv6-15-s-book/ip6-eui64.html
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