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1.0 Network Infrastructure and Connectivity

IPv6 Addressing Troubleshooting Practice Questions

Updated for CCNA v2.0

Modified EUI-64, prefix sizing, SLAAC prerequisites, and IPv6 address types.

CCNA v2.0 objective 1.4 · objective map

Author-reviewed by LabFabric · 25 September 2026 · Report a content issue

One solved question, so you can see how these are marked

An interface has the MAC address 0011.2233.4455. What is its modified EUI-64 interface identifier?

0211:22FF:FE33:4455

Split the MAC in half, insert FFFE in the middle, and flip the seventh bit of the first byte. 00 becomes 02, giving 0211:22FF:FE33:4455.

Every question in the set below is marked like this. The answers stay hidden until you pick one.

Find related practice in the CCNA path
Practise subnetting hands-onSee the 32 bits, split blocks into subnets, drill the 128/64/32/16/8/4/2/1 ladder, and practise the hex behind IPv6 (compression, prefixes, EUI-64). Free, in your browser.Open subnetting practice
All 9 IPv6 Addressing Troubleshooting questions in this set

Answers and explanations appear when you work through the set above.

  1. Which prefix length must a subnet have for SLAAC to work on an Ethernet LAN?

    • /64
    • /48
    • /126
    • /32

  2. IPv6 hosts on a LAN receive no global addresses and no default gateway. The router interface has a global address. Which global command is likely missing?

    • ipv6 unicast-routing
    • ipv6 enable
    • ip routing
    • ipv6 dhcp relay

  3. Which command combines the explicitly supplied prefix 2001:db8:1:1::/64 with a modified EUI-64 interface ID derived from the interface MAC address?

    • ipv6 address 2001:db8:1:1::/64 eui-64
    • ipv6 address autoconfig default
    • ipv6 address 2001:db8:1:1::1/64 link-local
    • ipv6 enable eui-64

  4. Which IPv6 address type begins with FE80::/10 and is required on every IPv6-enabled interface?

    • Link-local unicast
    • Global unicast
    • Unique local
    • Anycast

  5. Which range are global unicast addresses currently assigned from?

    • 2000::/3
    • FC00::/7
    • FF00::/8
    • FE80::/10

  6. An ISP delivers a /48 to a company. How many /64 subnets can the company create from it?

    • 65,536
    • 256
    • 4,096
    • 16

  7. Which command gives a quick summary of IPv6 addresses and interface status on a router?

    • show ipv6 interface brief
    • show ip interface brief
    • show ipv6 route summary only
    • show interfaces ipv6 status

  8. What does the solicited-node multicast address for the unicast address 2001:db8::1:2345:6789 look like?

    • FF02::1:FF45:6789
    • FF02::1
    • FF02::2
    • FF02::1:FF01:2345

  9. A router advertises a prefix with the A flag set, with M=0 and O=1. A DHCPv6-capable host receives the advertisement. What does the host do?

    • Builds its address by SLAAC, and obtains other settings such as DNS from stateless DHCPv6
    • Obtains its full address from DHCPv6
    • Ignores the router advertisement
    • Uses only a link-local address