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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.

Submitted by fatema_kw· Mar 5, 2026IP Connectivity

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

200-301 question #1457 exhibit 1
200-301 question #1457 exhibit 2

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)
  • A
    6% (2)
  • B
    3% (1)
  • C
    15% (5)
  • D
    76% (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.

A2001:db8:3bb8:3bb1:C810:B3FF:FF8B:1

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.

B2001:db8:3bb8:3bb1:C001:3BFE:FF81:1

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.

C2001:db8:3bb8:3bb4:6363:93FF:EF66:1

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.

D2001:db8:3bb8:3bb1:C801:B3FF:FEB8:1Correct

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

Topics

#IPv6 EUI-64#IPv6 Addressing#MAC address conversion

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