CCNA Practice Test 10 — 10 Questions

Question 1

Drag and drop the PDU names on the left to the correct OSI model layers on the right.

Accepted Answer

Segment: Transport layer PDU (TCP segment).. The correct matches are: Segment → Transport layer PDU, Packet → Network layer PDU, Frame → Data Link layer PDU, Bits → Physical layer PDU, and Data → Application layer PDU. No encapsulation term is included in this exercise.

Question 2

You are verifying OSPF operation on router R1. After confirming that OSPF is configured on the correct interfaces, which command should you use next to directly check whether R1 has established a neighbor adjacency with another OSPF router?

Accepted Answer

show ip ospf neighbor. The command show ip ospf neighbor directly displays the OSPF neighbor table, showing whether an adjacency has formed, the neighbor's Router ID, and the current state (e.g., FULL). This is the quickest verification step after confirming configurations. The other commands are unrelated to OSPF: show vlan brief displays VLAN assignments, show spanning-tree shows STP topology, and show mac address-table shows the MAC address table. None of these provide any OSPF neighbor information and would only delay troubleshooting.

Answer

show vlan brief

Answer

show spanning-tree

Answer

show mac address-table

Question 3

A host with address 172.16.5.10/23 wants to determine whether 172.16.6.20 is on the same local network. What is the correct conclusion?

Accepted Answer

It is on a different network, so the host should use the default gateway. A /23 prefix covers two consecutive /24 ranges. In plain language, that means the network boundaries move in blocks of 2 in the third octet. The address 172.16.5.10/23 belongs to the 172.16.4.0/23 network, which covers 172.16.4.x and 172.16.5.x. The destination 172.16.6.20 belongs to a different /23 block, so it is not on the same local network.

This question checks whether you can think beyond default /24 boundaries and understand how a broader prefix changes the local network range. The host would therefore need to use its default gateway to reach 172.16.6.20, because that destination is off-subnet relative to the /23 in use.

Answer

It is on the same local network because both addresses begin with 172.16.

Answer

It is on the same local network because /23 covers all addresses in 172.16.5.x and 172.16.6.x

Answer

It is on a different network, so ARP will resolve it across the router automatically

Question 4

Which THREE of the following best describe how agentic AI is used in network automation, specifically regarding AI agents, tool-calling, and closed-loop remediation workflows?

Accepted Answer

AI agents can autonomously decide which network troubleshooting steps to perform and invoke appropriate tools via APIs.. Options A, C, and D are correct because agentic AI in network automation involves autonomous decision-making (A), tool-calling to execute network commands or gather data (C), and closed-loop remediation that continuously monitors, diagnoses, and applies fixes automatically (D). Options B and E are incorrect because they contradict the autonomous nature of agentic AI: B describes a passive monitoring system with human-only remediation, and E states that closed-loop remediation always requires human approval, which is not true for full closed-loop automation.

Answer

AI agents only monitor network traffic and alert humans for any remediation actions.

Answer

Closed-loop remediation always requires a human to approve each corrective action before it is executed.

Question 5

A host is configured with IP address 172.16.100.222/27. Which address is the broadcast address for its subnet?

Accepted Answer

172.16.100.223. A /27 uses address blocks of 32. In practical terms, the fourth-octet ranges are 0–31, 32–63, 64–95, 96–127, 128–159, 160–191, 192–223, and 224–255. Since 222 falls inside the 192–223 block, the broadcast address is the last address in that block, which is 172.16.100.223.

This is a classic subnet-boundary question because it tests whether you can place a host in the correct block and then identify the final address in that block as the broadcast.

Answer

172.16.100.191

Answer

172.16.100.224

Answer

172.16.100.255

Question 6

Which two statements accurately describe the role of a switch MAC address table?

Accepted Answer

It maps learned MAC addresses to switch ports for local forwarding decisions.. A switch MAC address table helps the switch make local forwarding decisions efficiently. In plain language, the switch learns which MAC addresses appear on which ports and then uses that information to send frames only where they need to go instead of flooding every frame everywhere.

The MAC table is not the same thing as a routing table, and it is not used for OSPF neighbor storage or DHCP lease records.

Answer

It stores the best Layer 3 routes to remote networks.

Answer

It contains the router’s OSPF authentication keys.

Answer

It assigns IP addresses to end hosts dynamically.

Question 7

A subnet requires 200 usable host addresses. Which prefix is the smallest that meets the requirement?

Accepted Answer

/24. A /24 is the smallest valid choice. In plain language, the subnet needs enough total addresses so that after the network and broadcast addresses are reserved, 200 hosts still remain. A /25 is too small because it provides only 126 usable hosts. A /24 provides 254 usable hosts, which satisfies the requirement while being the next logical prefix size up.

This is a standard host-capacity planning question. The key is to work from usable hosts, not just total addresses, and then choose the smallest prefix that actually works.

Answer

/25

Answer

/26

Answer

/27

Question 8

Drag and drop the following steps into the correct order to explicitly configure OSPFv3 for IPv6 on a Cisco IOS-XE router, assuming no OSPFv3 routing process exists beforehand.

Accepted Answer

Enable IPv6 unicast routing globally. To configure OSPFv3, first globally enable IPv6 unicast routing (A). Next, create the OSPFv3 routing process (C) so that it is defined before interfaces try to use it. Then, configure OSPFv3 on the relevant interfaces (B) to activate routing. Finally, verify the OSPFv3 adjacency (D) to confirm neighbors are formed. This sequence avoids automatic process creation and ensures all steps are explicitly controlled.

Question 9

An engineer is deploying a new Cisco Catalyst 9300 switch in a campus wiring closet. The uplink to the distribution switch uses a 1000BASE-LX SFP module. After connecting the fiber, the interface shows 'up/up' but the engineer notices that the 'input errors' counter is incrementing rapidly, with many CRC errors, runts, and giants being reported. What is the most likely cause of these input errors?

Accepted Answer

Check the fiber distance and ensure it is within the 5 km limit for 1000BASE-LX; if over, use a single-mode fiber extender.. The 1000BASE-LX standard uses long-wavelength laser optics (1300 nm) over single-mode fiber with a maximum distance of 5 km. Exceeding this limit causes signal attenuation and dispersion, generating bit errors that corrupt the frame check sequence (FCS). Cisco IOS counts these as CRC errors. Runts (frames shorter than 64 bytes) and giants (frames longer than 1518 bytes) also appear because the damaged frames are misinterpreted. Option B correctly identifies the distance limit as the root cause and recommends verifying it or using a fiber extender. Options A and D propose incorrect media, and option C would break the link since 1000BASE-LX operates at fixed 1000/full speed.

Answer

Replace the SFP with a 1000BASE-SX module.

Answer

Configure the interface with 'speed 100' and 'duplex full' to match the SFP capabilities.

Answer

Replace the fiber patch cable with a CAT6a copper cable and use a 1000BASE-T SFP.

Question 10

Which two statements accurately describe UDP compared with TCP?

Accepted Answer

UDP is connectionless.. UDP is designed for simplicity and speed rather than built-in reliability. In plain terms, it sends data without creating a formal conversation first. That is why it is called connectionless. Because it does not perform the same reliability features as TCP, its header is smaller and the protocol adds less overhead. This makes UDP a good fit for applications that care more about speed or low delay than guaranteed delivery at the transport layer.

UDP does not perform a three-way handshake, and it does not guarantee delivery. It is also used by many real services, including DNS in common query scenarios.

Answer

UDP always guarantees delivery and sequencing.

Answer

UDP requires a three-way handshake before application data can be sent.

Answer

UDP cannot be used by DNS.