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200-301 · Question #1507

Refer to the exhibit. The IPv6 address for the LAN segment on router R2 must be configured using the EUI-64 format. When configured which ipv6 address is produced by the router?

The correct answer is D. 2001:db8:9bb6:6bb9:C801:B6FF:FEB8:1. The EUI-64 format generates an IPv6 interface ID by splitting a 48-bit MAC address, inserting FFFE in the middle, and flipping the 7th bit of the first byte.

Submitted by carter_n· Mar 5, 2026

Question

Refer to the exhibit. The IPv6 address for the LAN segment on router R2 must be configured using the EUI-64 format. When configured which ipv6 address is produced by the router?

Exhibits

200-301 question #1507 exhibit 1
200-301 question #1507 exhibit 2

Options

  • A2001:db8:9bb6:6bb9:C801:B6FF:FFB4:1
  • B2001:db8:9bb6:6bb9:C001:6BFE:FF01:1
  • C2001:db8:9bb6:6bb9:4679:824F:FE88:1
  • D2001:db8:9bb6:6bb9:C801:B6FF:FEB8:1

How the community answered

(27 responses)
  • A
    11% (3)
  • B
    4% (1)
  • C
    7% (2)
  • D
    78% (21)

Why each option

The EUI-64 format generates an IPv6 interface ID by splitting a 48-bit MAC address, inserting FFFE in the middle, and flipping the 7th bit of the first byte.

A2001:db8:9bb6:6bb9:C801:B6FF:FFB4:1

This option does not correctly apply the EUI-64 transformation rules, specifically the insertion of FFFE and the flipping of the 7th bit from the presumed MAC address.

B2001:db8:9bb6:6bb9:C001:6BFE:FF01:1

This option incorrectly generates the interface ID, as it does not follow the EUI-64 process of splitting the MAC, inserting FFFE, and flipping the 7th bit of the first octet.

C2001:db8:9bb6:6bb9:4679:824F:FE88:1

This option shows an interface ID that is not derived by the EUI-64 method from a standard MAC address due to incorrect bit manipulation and FFFE insertion.

D2001:db8:9bb6:6bb9:C801:B6FF:FEB8:1Correct

The EUI-64 process for an interface ID starts by taking a 48-bit MAC address (e.g., CA:01:B6:B8:00:01), inserting 'FFFE' in the middle (CA01:B6FF:FEB8:0001), and then flipping the 7th bit of the first byte (the Universal/Local bit). For the MAC address CA:01:B6:B8:00:01, the first byte CA (11001010 in binary) has its 7th bit (bit 6, 0-indexed from left) as 1; flipping this bit to 0 results in C8 (11001000), producing the interface ID C801:B6FF:FEB8:0001, which when combined with the prefix 2001:db8:9bb6:6bb9::/64 yields 2001:db8:9bb6:6bb9:C801:B6FF:FEB8:1.

Concept tested: IPv6 EUI-64 address generation

Source: https://learn.microsoft.com/en-us/windows/win32/iphlpapi/eui-64-address

Topics

#IPv6 EUI-64#IPv6 addressing#Router IPv6 configuration

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