CCNA Network Infrastructure and Connectivity Practice Test 9 — 15 Questions

Question 1

A switch port and a host NIC have a duplex mismatch. Which symptom is most likely?

Accepted Answer

Increased late collisions and poor performance. A duplex mismatch often causes collisions, frame errors, and degraded throughput, especially on the half-duplex side. It is a classic physical/link layer performance problem.

Answer

Incorrect VLAN tagging on trunks

Answer

OSPF area mismatch errors

Answer

A change in the subnet mask on the host

Question 2

Which rule does a router apply first when selecting a route for a destination packet?

Accepted Answer

Longest prefix match. Routers first look for the most specific matching prefix. Administrative distance and metrics matter when competing routes exist for the same destination prefix length.

Answer

Lowest metric across all protocols

Answer

Oldest route in the routing table

Answer

Default route if one exists

Question 3

Why does traceroute reveal each router hop along a path?

Accepted Answer

Each router decrements TTL or hop limit, and expired packets trigger ICMP messages. Traceroute sends packets with increasing TTL or hop-limit values. When the value expires, the router that drops the packet returns an ICMP message, identifying that hop.

Answer

Each router appends its hostname to the packet payload

Answer

Each router sends an ARP response back to the source

Answer

Each switch on the path sends a syslog message to the source host

Question 4

Which IPv6 protocol function replaces ARP?

Accepted Answer

Neighbor Discovery. IPv6 uses Neighbor Discovery Protocol to resolve Layer 3-to-Layer 2 information and perform related local-link functions such as router discovery and address resolution.

Answer

DHCPv6

Answer

EUI-64

Answer

SLAAC

Question 5

A branch LAN requires 50 usable IPv4 host addresses. What is the most efficient subnet mask that provides at least 50 usable hosts?

Accepted Answer

/26. A /26 provides 64 total addresses and 62 usable host addresses, which is the smallest subnet mask (largest prefix length) that fits 50 hosts, making it the most efficient choice.

Answer

/27

Answer

/25

Answer

/24

Question 6

Which cable type is commonly used to connect a switch to a router when using standard Ethernet interfaces on modern devices with auto-MDIX support?

Accepted Answer

Straight-through Ethernet cable. A straight-through Ethernet cable is the common expected answer for switch-to-router Ethernet connections. On modern interfaces, auto-MDIX often makes crossover requirements less important in practice.

Answer

Rollover cable

Answer

Serial DCE cable

Answer

Fiber patch cable only

Question 7

A host address is 2001:db8:100:20::25/64. Which portion identifies the network prefix?

Accepted Answer

2001:db8:100:20. With a /64 prefix, the first 64 bits identify the network. That corresponds to the first four hextets: 2001:db8:100:20.

Answer

2001:db8:100

Answer

2001:db8:100:20::25

Answer

::25

Question 8

Which IPv6 prefix is used for link-local addresses?

Accepted Answer

FE80::/10. IPv6 link-local addresses come from FE80::/10. They are valid only on the local link and are commonly used for neighbor discovery and routing adjacency formation.

Answer

FC00::/7

Answer

2000::/3

Answer

FF00::/8

Question 9

Which IPv6 address type is automatically created on an interface and used for link-local communication?

Accepted Answer

Link-local. IPv6 interfaces automatically generate a link-local address in FE80::/10 for local-segment functions such as neighbor discovery.

Answer

Unique local

Answer

Global unicast

Answer

Anycast

Question 10

Which two statements about ARP on an IPv4 Ethernet network are correct? (Choose two.)

Accepted Answer

An ARP request is sent as a Layer 2 broadcast.. ARP resolves an IPv4 address to a MAC address on the local segment. ARP requests are broadcast; ARP replies are typically unicast.

Answer

ARP is used to map IPv6 addresses to MAC addresses.

Answer

ARP is forwarded by routers across subnets by default.

Question 11

A switch displays the following output:

Interface        Status         VLAN
Gi1/0/5          connected      20
Gi1/0/6          notconnect     1
Gi1/0/24         trunk          trunk

Which interface is operating as an access port in VLAN 20?

Accepted Answer

Gi1/0/5. The output explicitly shows Gi1/0/5 in VLAN 20 and not operating as a trunk.

Answer

Gi1/0/6

Answer

Gi1/0/24

Answer

None of the interfaces

Question 12

Which OSI layer is responsible for end-to-end segmentation, port numbers, and reliability functions such as acknowledgments?

Accepted Answer

Transport. The Transport layer (Layer 4) is responsible for end-to-end segmentation, port numbers for identifying applications, and reliability functions like acknowledgments and retransmission. The Network layer (Layer 3) handles logical addressing and routing between networks. The Data Link layer (Layer 2) manages local frame delivery and error detection. The Session layer (Layer 5) controls dialog management and synchronization, not segmentation or ports.

Answer

Network

Answer

Data Link

Answer

Session

Question 13

A router interface is configured with 192.0.2.97/28. What is the network address of the subnet?

Accepted Answer

192.0.2.96. A /28 uses blocks of 16 addresses. The block containing .97 runs from .96 through .111, so .96 is the network address.

Answer

192.0.2.80

Answer

192.0.2.111

Answer

192.0.2.112

Question 14

A host with IP address 172.16.50.130 and mask 255.255.255.192 needs to reach 172.16.50.190. Which statement is correct?

Accepted Answer

The destination is local, so the host ARPs for 172.16.50.190 directly.. Both 172.16.50.130 and 172.16.50.190 fall within the 172.16.50.128/26 subnet (range .128 to .191). Therefore, the destination is local, and the host will use ARP to resolve the destination IP directly. Option A is incorrect because the destination is not remote. Option C is incorrect because the directed broadcast address for this subnet is 172.16.50.191, not .190. Option D is incorrect because 172.16.50.130 is a valid host address, not the network address (.128).

Answer

The destination is on a remote subnet, so the host must send to the default gateway.

Answer

The destination is a directed broadcast for the local subnet.

Answer

The source host is using the network address of the subnet.

Question 15

A company wants private IPv4 addressing that can be routed internally but not on the public Internet. Which range meets that requirement?

Accepted Answer

172.20.0.0/16. RFC 1918 defines private IPv4 ranges for internal routing: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. 172.20.0.0/16 falls within the 172.16.0.0/12 block, making it a valid private address. 198.51.100.0/24 is reserved for documentation (TEST-NET-2) and should not be used internally. 169.254.0.0/16 is link-local (APIPA), used only for automatic addressing on a single link. 224.0.0.0/4 is multicast, not routable as unicast and not private.

Answer

198.51.100.0/24

Answer

169.254.0.0/16

Answer

224.0.0.0/4