CCNA Network Infrastructure and Connectivity Practice Test 14 — 15 Questions

Question 1

A router interface is configured with the prefix 2001:db8:acad:12::/64 and uses EUI-64 to build the interface ID. What is the main purpose of EUI-64 in this context?

Accepted Answer

It automatically creates the interface ID portion of the IPv6 address from the MAC address.. EUI-64 is used to automatically generate the interface identifier portion of the IPv6 address from the underlying MAC address. In practical terms, the /64 prefix provides the network portion, and EUI-64 helps derive the lower 64 bits without the administrator manually typing a full host portion. This can make addressing easier in environments where automatic formation is desired.

The important idea is that EUI-64 affects the interface ID, not the prefix length or the routing behavior of the network. It is an address-construction method, not a routing protocol.

Answer

It changes the /64 prefix into a /48 prefix for summarization.

Answer

It replaces the need for a link-local address.

Answer

It encrypts IPv6 traffic between neighbors.

Question 2

A host uses the subnet mask 255.255.255.240. How many usable host addresses exist in each subnet?

Accepted Answer

14. The mask 255.255.255.240 corresponds to /28. In practical terms, that leaves 4 host bits, which gives 16 total addresses in each subnet. After subtracting the network and broadcast addresses, 14 usable hosts remain.

This is a classic host-capacity calculation and a very common subnetting pattern on the exam.

Answer

12

Answer

16

Answer

30

Question 3

A host address is 10.10.10.14/29. Which address is the broadcast address for its subnet?

Accepted Answer

10.10.10.15. A /29 subnet has a block size of 8. In practical terms, the fourth-octet ranges are 0–7, 8–15, 16–23, and so on. Since 14 falls in the 8–15 block, the broadcast address is the last address in that block, which is 10.10.10.15.

This is a classic subnetting question that checks whether you can find the block first and then identify the final address in that block.

Answer

10.10.10.7

Answer

10.10.10.8

Answer

10.10.10.16

Question 4

Match each IPv6 concept to its most accurate description.

Accepted Answer

IPv6 address: 128-bit identifier for network interfaces. These pairings accurately define key IPv6 concepts.

Question 5

A host is configured with IP address 192.168.70.18/30. Which addresses belong to the same subnet block?

Accepted Answer

192.168.70.16 through 192.168.70.19. A /30 subnet has a block size of 4. In practical terms, the relevant blocks in the last octet are 0–3, 4–7, 8–11, 12–15, 16–19, and so on. Because 18 falls inside the 16–19 block, the subnet includes network address .16, usable hosts .17 and .18, and broadcast .19.

This question checks whether you can identify the correct /30 block and understand all addresses that fall inside it.

Answer

192.168.70.18 through 192.168.70.21

Answer

192.168.70.12 through 192.168.70.15

Answer

192.168.70.20 through 192.168.70.23

Question 6

A host uses subnet mask 255.255.255.224. How many total addresses exist in each subnet block?

Accepted Answer

32. The subnet mask 255.255.255.224 (/27) has 5 host bits, so each subnet has 2^5 = 32 total addresses. Option A (16) results from confusing /27 with /28 (4 host bits = 16). Option D (64) results from confusing /27 with /26 (6 host bits = 64). Option C (30) is the number of usable host addresses (32 - 2 = 30), not the total addresses asked for in the question.

Answer

16

Answer

30

Answer

64

Question 7

An IPv6 host has a global unicast address and a correct default route learned from a router advertisement, but the next-hop entry shown on the host uses a link-local address rather than a global unicast address. What is the best explanation?

Accepted Answer

IPv6 hosts commonly use the router’s link-local address as the next hop on the local segment.. That behavior is normal in IPv6. In practical terms, the host only needs to reach the router on the local segment, so it uses the router’s link-local address as the next-hop target. The packet still leaves the local link toward remote destinations, but the immediate neighbor on that link is identified by link-local addressing.

This is an important IPv6 concept because many people assume the default gateway must be a globally routable address. It does not. On the local link, the host is really forwarding to its directly attached router interface, and the router’s link-local address is enough for that local handoff.

Answer

The host has learned the wrong default route because IPv6 gateways must always be global unicast.

Answer

The host can reach only local destinations when the next hop is link-local.

Answer

The router advertisement has failed because it did not provide a MAC address.

Question 8

A subnet uses the mask 255.255.255.252. How many usable host addresses are available in each subnet?

Accepted Answer

2. The mask 255.255.255.252 corresponds to /30. In practical terms, that gives 4 total addresses per subnet. After subtracting the network and broadcast addresses, 2 usable host addresses remain.

This is a classic small-subnet calculation that often appears in point-to-point addressing scenarios.

Answer

4

Answer

6

Answer

14

Question 9

An IPv6 host successfully reaches neighbors on its local segment, but it cannot reach remote IPv6 destinations. The host has a global unicast address and a correct prefix length. Which missing item is the strongest suspect?

Accepted Answer

A usable default router or next-hop route for off-link IPv6 traffic. The strongest suspect is the absence of a usable default router learned through IPv6 router advertisements or equivalent configuration. While local connectivity works because the host can communicate on its own link, remote IPv6 destinations require a next hop off the local segment. Option B is wrong because IPv6-to-IPv4 NAT is unnecessary for native IPv6 communication and would not be the primary cause of off-link failure. Option C is wrong because a VLAN trunk on the host NIC is for carrying multiple VLANs, not for enabling off-link routing. Option D is wrong because a second global unicast address does not provide a default route; it only adds another local address.

Answer

A NAT rule translating IPv6 to IPv4

Answer

A VLAN trunk on the host NIC

Answer

A second global unicast address on the same interface

Question 10

A host is configured with 10.1.1.34/30. Which address is the broadcast address for its subnet?

Accepted Answer

10.1.1.35. A /30 subnet has a block size of 4. In practical terms, the last-octet blocks are 0–3, 4–7, 8–11, and so on. Because 34 falls within the 32–35 block, the broadcast address is the last address in that block: 10.1.1.35.

This question tests whether you can identify the correct subnet block before choosing the broadcast address.

Answer

10.1.1.31

Answer

10.1.1.32

Answer

10.1.1.36

Question 11

A host address is 192.168.88.66/27. Which address is the network address of the subnet?

Accepted Answer

192.168.88.64. A /27 subnet has a block size of 32. In practical terms, the fourth-octet ranges are 0-31, 32-63, 64-95, and so on. Because 66 falls within the 64-95 block, the network address is 192.168.88.64.

This is a classic subnet-boundary calculation. The key step is identifying the correct block first.

Answer

192.168.88.32

Answer

192.168.88.95

Answer

192.168.88.96

Question 12

Which two statements accurately describe the relationship between a network address and a broadcast address in IPv4 subnetting?

Accepted Answer

The network address is the first address in the subnet block.. The network address identifies the beginning of the subnet block, and the broadcast address identifies the final address in that block. In practical terms, both are reserved and are not assigned to ordinary hosts. The usable host range falls between them.

This is a very basic subnetting truth, but it is foundational for every other addressing calculation.

Answer

Both addresses are normal host addresses that can be assigned to users.

Answer

The broadcast address always becomes the default gateway.

Answer

These concepts exist only in IPv6 and not IPv4.

Question 13

A host address is 192.168.14.222/28. Which address is the broadcast address of its subnet?

Accepted Answer

192.168.14.223. A /28 subnet has a block size of 16. In practical terms, the fourth-octet blocks are 0-15, 16-31, and so on. Because 222 falls within the 208-223 block, the broadcast address is the last address in that block: 192.168.14.223.

This is a subnet-boundary question that depends on identifying the correct /28 block before choosing the broadcast address.

Answer

192.168.14.207

Answer

192.168.14.208

Answer

192.168.14.224

Question 14

In a network running STP, SW2 became the root bridge for VLAN 10. Both SW1 and SW2 have the same bridge priority. Why did SW2 become the root?

Accepted Answer

Because SW2 has the lower bridge ID due to the lower MAC address.. SW2 became the root bridge because its bridge ID is lower. In practical terms, spanning tree elects the root bridge by comparing bridge IDs, which are based on priority plus MAC address. The device with the lowest bridge ID wins. In the exhibit, both switches use the same priority, so the tie is broken by the lower MAC address.

This is a classic STP interpretation question. Many learners focus only on priority, but if priorities match, the MAC address becomes decisive.

Answer

Because SW2 has the higher VLAN number configured.

Answer

Because SW2 has more trunk ports than SW1.

Answer

Because SW2 has the highest bridge priority.

Question 15

A host address is 192.168.50.158/27. Which address is the network address of its subnet?

Accepted Answer

192.168.50.128. A /27 subnet has a block size of 32. In practical terms, the relevant ranges in the last octet are 0-31, 32-63, 64-95, 96-127, 128-159, and so on. Because 158 falls in the 128-159 block, the network address is 192.168.50.128.

This is a block-identification question. Once you identify the correct /27 block, the network address is the first address in that range.

Answer

192.168.50.159

Answer

192.168.50.160

Answer

192.168.50.96