Cisco CCNA IPv4 and IPv6 Addressing 4 — Questions and Answers
Question 1: A host has the IP address 10.4.8.77/21. What is the network address of this subnet?
- 10.4.8.0
- 10.4.0.0 (Correct answer)
- 10.4.8.64
- 10.0.0.0
Correct answer: 10.4.0.0
A /21 mask covers the first 21 bits; the third octet's top 5 bits identify the subnet — 8 (00001000) ANDed with the mask gives 10.4.0.0.
Question 2: What is the purpose of the IPv6 EUI-64 process?
- To assign a /64 prefix from a DHCPv6 server
- To generate a 64-bit interface ID from a 48-bit MAC address (Correct answer)
- To compress consecutive zeros in an IPv6 address
- To convert an IPv4 address to IPv6 format
Correct answer: To generate a 64-bit interface ID from a 48-bit MAC address
EUI-64 inserts FFFE in the middle of a 48-bit MAC address and flips the 7th bit to create a unique 64-bit interface ID.
Question 3: Which statement correctly describes VLSM (Variable Length Subnet Masking)?
- All subnets must use the same prefix length
- Subnets can use different prefix lengths to optimize address space (Correct answer)
- VLSM is only supported in IPv6
- VLSM requires classful routing protocols
Correct answer: Subnets can use different prefix lengths to optimize address space
VLSM allows different subnets within the same address space to use different prefix lengths, enabling efficient IP address utilization.
Question 4: Which IPv4 address block is used for APIPA (Automatic Private IP Addressing) when DHCP is unavailable?
- 192.168.0.0/16
- 172.16.0.0/12
- 169.254.0.0/16 (Correct answer)
- 10.0.0.0/8
Correct answer: 169.254.0.0/16
Windows assigns APIPA addresses from 169.254.0.0/16 when a DHCP server cannot be reached.
Question 5: How many bits make up an IPv6 address?
- 32
- 64
- 128 (Correct answer)
- 256
Correct answer: 128
IPv6 addresses are 128 bits long, expressed as eight groups of four hexadecimal digits.
Question 6: A router interface is configured with 'ipv6 address 2001:DB8:A:1::/64 eui-64'. What does the eui-64 keyword cause the router to do?
- Use a randomly generated interface ID
- Derive the interface ID from the interface's MAC address using EUI-64 (Correct answer)
- Use DHCPv6 to obtain the full address
- Configure only the prefix without an interface ID
Correct answer: Derive the interface ID from the interface's MAC address using EUI-64
The eui-64 keyword instructs the router to generate the 64-bit interface ID automatically from the interface's MAC address using the EUI-64 method.
Question 7: Which subnet contains the host address 192.168.5.200/27?
- 192.168.5.160/27
- 192.168.5.192/27 (Correct answer)
- 192.168.5.176/27
- 192.168.5.224/27
Correct answer: 192.168.5.192/27
With /27 (block size 32), subnet boundaries are .0, .32, .64, .96, .128, .160, .192, .224 — the address .200 falls in the 192.168.5.192/27 subnet.
Cisco CCNA IPv4 and IPv6 Addressing 4
A host has the IP address 10.4.8.77/21.
What is the network address of this subnet?