CompTIA Network+ N10-009 Practice Test: 20 Free Questions with Answers

Twenty questions in the exam's domain weights, each with its answer and the reason. The full course has 367 explained questions plus generated math items, scored tests in the real exam's format, and lessons built from what you miss.

1. A company connects its offices in Denver, Atlanta, and Seattle using circuits leased from a telecommunications provider. Which term BEST describes this network?

   1. LAN
   2. WAN
   3. PAN
   4. SAN
   Show the answer

   Answer: B. A WAN connects LANs across geographic distance, typically over provider links. A LAN is a single site, a PAN is personal-range such as Bluetooth, and a SAN is dedicated storage networking.

   From the lesson Networks and Their Types.

2. A network requires that a failure of any single link never isolates a site. Which topology provides the MOST redundancy?

   1. Star
   2. Bus
   3. Full mesh
   4. Ring
   Show the answer

   Answer: C. Full mesh connects every node to every other node, so any single link can fail without cutting a path. It is the most redundant and the most expensive.

   From the lesson Physical and Logical Topologies.

3. In a data center fabric, every leaf switch connects to every spine switch and no leaf connects to another leaf. What is the maximum number of switch hops between any two servers?

   1. One
   2. It depends on the number of leaves
   3. Three
   4. Two
   Show the answer

   Answer: D. In spine and leaf, traffic goes leaf to spine to leaf, so any two servers are at most two hops apart with predictable latency.

   From the lesson Enterprise Architectures and Traffic Flow.

4. A technician replaces a damaged patch cable to restore a link. At which OSI layer was the problem?

   1. Layer 1
   2. Layer 2
   3. Layer 3
   4. Layer 4
   Show the answer

   Answer: A. Cables, connectors, and signaling are Physical layer, Layer 1.

   From the lesson Layers 1 to 3: Physical, Data Link, Network.

5. A switch receives a frame whose destination MAC address is not in its MAC address table. What does it do?

   1. Drops the frame
   2. Floods the frame out all ports in the VLAN except the one it arrived on
   3. Forwards the frame to the default gateway port so the router can resolve the destination
   4. Sends an ARP request
   Show the answer

   Answer: B. Unknown unicast frames are flooded within the VLAN so the destination can respond and the switch can learn its port.

   From the lesson How Switches Work.

6. Two switches must be connected by one link that carries traffic for VLANs 10, 20, and 30. How should the ports on each end be configured?

   1. As access ports in VLAN 1
   2. With port mirroring
   3. As an 802.1Q trunk
   4. As a voice VLAN
   Show the answer

   Answer: C. An 802.1Q trunk tags each frame with its VLAN ID so multiple VLANs can share one physical link.

   From the lesson VLANs and Trunking.

7. After a technician adds a second cable between two switches for redundancy, the network floods with broadcast traffic and becomes unusable. Which protocol, if enabled, would have prevented this?

   1. LACP
   2. VRRP
   3. LLDP
   4. STP
   Show the answer

   Answer: D. Spanning Tree Protocol blocks redundant Layer 2 paths to prevent loops and broadcast storms. LACP would bundle the links but must be deliberately configured.

   From the lesson Spanning Tree Protocol.

8. A new access point requires about 25 watts over its Ethernet cable. Which PoE standard must the switch port support at minimum?

   1. 802.3at
   2. 802.3af
   3. 802.3bt Type 4
   4. 802.1X
   Show the answer

   Answer: A. 802.3af delivers about 13 watts to the device. 802.3at, PoE+, delivers about 25.5 watts. 802.3bt goes to 60 and 90 watts.

   From the lesson Switch Interface Features.

9. Clients on a remote subnet with no local DHCP server fail to obtain addresses. What should be configured on the router interface for that subnet?

   1. A DHCP reservation
   2. A DHCP relay, also called an IP helper address
   3. A DHCP exclusion covering the remote subnet's range on the central server
   4. A DNS forwarder pointing the remote clients at the central resolver
   Show the answer

   Answer: B. DHCP Discover is a broadcast that routers do not forward. A relay converts it to a unicast to the central server.

   From the lesson DHCP.

10. Which DNS record type resolves an IP address back to a hostname?

    1. A
    2. MX
    3. PTR
    4. TXT
    Show the answer

    Answer: C. PTR records live in the reverse zone and map addresses to names.

    From the lesson DNS.

11. Users cannot log in to the domain after a switch's clock drifted 20 minutes from the domain controllers. Which service should be fixed?

    1. DNS
    2. SNMP
    3. DHCP
    4. NTP
    Show the answer

    Answer: D. Kerberos authentication fails when clocks differ by more than about five minutes. NTP keeps them synchronized.

    From the lesson Time Services and Other Network Services.

12. Which document shows how traffic flows between networks, including IP addressing, VLANs, and routing, rather than where devices physically sit?

    1. Logical network diagram
    2. Physical network diagram
    3. Rack diagram
    4. Cable map
    Show the answer

    Answer: A. Logical diagrams depict addressing and data flow. Physical diagrams, rack diagrams, and cable maps show location and wiring.

    From the lesson Documentation.

13. A user signs in with a password and then enters a six-digit code from an authenticator app on their phone. Which factor types are in use?

    1. Something you know and something you are
    2. Something you know and something you have
    3. Something you have and somewhere you are
    4. Two instances of something you know
    Show the answer

    Answer: B. The password is knowledge; the TOTP app on a possessed device is possession. A fingerprint would be inherence.

    From the lesson Security Concepts.

14. An attacker sets up a wireless access point broadcasting the same SSID as the corporate network so that users connect to it instead. What is this attack called?

    1. Rogue DHCP server
    2. Deauthentication attack
    3. Evil twin
    4. Phishing
    Show the answer

    Answer: C. An evil twin impersonates a legitimate SSID to capture traffic and credentials.

    From the lesson Common Attacks.

15. A company wants only laptops with current antivirus and patches to join the LAN, and wants noncompliant devices moved to a remediation VLAN automatically. Which technology provides this?

    1. A honeypot
    2. Port mirroring that copies LAN traffic to an IDS sensor
    3. Content filtering on the internet gateway
    4. Network access control with posture assessment
    Show the answer

    Answer: D. NAC checks device health at connection time and quarantines devices that fail.

    From the lesson Defense and Hardening.

16. A technician has tested a theory and confirmed the actual cause of a network problem. According to the troubleshooting methodology, what is the NEXT step?

    1. Implement the solution immediately, since testing has already confirmed the cause
    2. Establish a plan of action and identify potential effects
    3. Verify full system functionality
    4. Document findings
    Show the answer

    Answer: B. After confirming the cause, plan the fix and consider its side effects before implementing.

    From the lesson The Troubleshooting Methodology.

17. A switch interface connected to another switch shows a rapidly increasing CRC error counter. What is the MOST likely cause?

    1. An exhausted DHCP scope
    2. An incorrect VLAN assignment on the trunk between the switches
    3. A damaged cable, interference, or a duplex mismatch
    4. A misconfigured default gateway on the downstream switch's management interface
    Show the answer

    Answer: C. CRC errors mean frames arrived corrupted, which points to Layer 1 or 2 issues such as cabling, EMI, or duplex mismatch.

    From the lesson Cabling and Physical Interface Problems.

18. After a technician connects two switches with an extra cable, all users on the floor lose connectivity, switch CPUs spike, and MAC addresses flap between ports. What is happening?

    1. DHCP scope exhaustion
    2. An ACL is blocking traffic
    3. A DNS outage
    4. A Layer 2 loop and broadcast storm
    Show the answer

    Answer: D. A redundant link without functioning spanning tree creates a loop. Broadcasts multiply until the switches are overwhelmed.

    From the lesson Network Service Problems.

19. Users in one area report slow Wi-Fi despite full signal strength. A survey shows three nearby access points all operating on channel 6. What is the MOST likely cause?

    1. Channel overlap causing co-channel interference
    2. Attenuation from walls and ceilings between the clients and the AP
    3. Weak encryption
    4. Roaming misconfiguration keeping clients on a distant AP
    Show the answer

    Answer: A. Strong signal rules out coverage. APs sharing a channel must share airtime, collapsing throughput. Spread them across 1, 6, and 11.

    From the lesson Performance and Wireless Problems.

20. A technician needs to find at which hop along the path to a remote server packets are being lost. Which tool is BEST?

    1. ping with a large packet count
    2. traceroute or tracert
    3. nslookup
    4. arp
    Show the answer

    Answer: B. Traceroute shows every hop and its response time, so you can see where loss begins. Ping only tests end to end.

    From the lesson Software Tools and Commands.