Networking Fundamentals & OSI Model practice test: free CompTIA Network+ (N10-009) questions

Sample Practice Questions for Networking Fundamentals & OSI Model

1. Question 1Ref: CompTIA Network+ N10-009 — Networking Concepts: OSI Model, 23%

   A network technician is configuring a device that operates at Layer 3 of the OSI model and makes forwarding decisions based on IP addresses. Which device is the technician most likely configuring?

   ASwitchBRouterCHubDBridge
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   Correct Answer
   B. Router

   The keyed answer is "Router". Routers operate at Layer 3 (Network) of the OSI model and use IP addresses to make forwarding decisions. Switches work at Layer 2 using MAC addresses, hubs repeat signals at Layer 1, and bridges filter traffic at Layer 2.

2. Question 2Ref: CompTIA Network+ N10-009 — Networking Concepts: IPv4 Addressing, 23%

   A network administrator needs to assign a private IP address to a workstation on a LAN. Which of the following addresses falls within the RFC 1918 private range for Class B networks?

   A192.168.1.50B10.0.0.15C172.16.4.92D128.0.0.1
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   Correct Answer
   C. 172.16.4.92

   The keyed answer is "172.16.4.92". RFC 1918 defines private Class B ranges as 172.16.0.0 through 172.31.255.255. The 192.168.x.x range is Class C private, 10.x.x.x is Class A private, and 128.0.0.1 is a public address.

3. Question 3Ref: CompTIA Network+ N10-009 — Networking Concepts: IPv4 Addressing, 23%

   A user reports they can reach internal servers but not external websites. Which default gateway issue would cause this symptom?

   AGateway IP is on the wrong subnetBGateway MAC address is mismatchedCGateway firewall blocks all outboundDDNS server is unreachable
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   Correct Answer
   C. Gateway firewall blocks all outbound

   The keyed answer is "Gateway firewall blocks all outbound". If the default gateway firewall blocks all outbound traffic, internal communication works (same subnet) but external traffic is dropped. A wrong subnet gateway or DNS failure would affect all resolution or routing.

4. Question 4Ref: CompTIA Network+ N10-009 — Networking Concepts: Cloud Computing, 23%

   A company deploys a cloud environment where the network administrator manages virtual switches and subnets but not the underlying physical hosts. Which cloud service model is being used?

   ASoftware as a ServiceBPlatform as a ServiceCFunction as a ServiceDInfrastructure as a Service
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   Correct Answer
   D. Infrastructure as a Service

   The keyed answer is "Infrastructure as a Service". IaaS provides virtualized networking, compute, and storage where the customer manages OS and network configuration but not the physical hardware. SaaS delivers applications, PaaS provides a development platform, and FaaS is serverless compute.

5. Question 5Ref: CompTIA Network+ N10-009 — Networking Concepts: IPv4 Addressing, 23%

   An administrator is troubleshooting a host that received an IP address of 169.254.12.8. What does this indicate?

   AThe host has a static IP configuredBThe host is using IPv6 link-local addressingCThe host could not reach a DHCP serverDThe host is on a different VLAN
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   Correct Answer
   C. The host could not reach a DHCP server

   The keyed answer is "The host could not reach a DHCP server". APIPA (Automatic Private IP Addressing) assigns a 169.254.x.x address when a DHCP server is unreachable. This allows local-link communication only and indicates a DHCP failure.

6. Question 6Ref: CompTIA Network+ N10-009 — Networking Concepts: Transmission Media, 23%

   A network engineer needs to connect two buildings 300 meters apart using fiber. Which fiber type is the most cost-effective choice for this distance?

   ASingle-mode fiberBMultimode fiberCCat6a twisted pairDCoaxial cable
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   Correct Answer
   B. Multimode fiber

   The keyed answer is "Multimode fiber". Multimode fiber supports distances up to about 550 meters and is cheaper than single-mode for short-to-medium runs. Single-mode supports longer distances but requires more expensive transceivers.

7. Question 7Ref: CompTIA Network+ N10-009 — Infrastructure: Routing Technologies, 20%

   A technician runs a command that shows a default route of 0.0.0.0/0 pointing to 10.0.0.1. What is the purpose of this route?

   ASends all unmatched traffic to the specified gatewayBDirects traffic for the 10.0.0.0 network locallyCPrevents routing loops within the autonomous systemDPrioritizes traffic for quality of service
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   Correct Answer
   A. Sends all unmatched traffic to the specified gateway

   The keyed answer is "Sends all unmatched traffic to the specified gateway". A default route (0.0.0.0/0) matches any destination not explicitly in the routing table and forwards packets to the next-hop gateway. It acts as a catch-all for all outbound traffic.

8. Question 8Ref: CompTIA Network+ N10-009 — Networking Concepts: Networking Appliances, 23%

   A company needs to load balance incoming web traffic across three servers. Which device or technology is best suited for this task?

   ADNS round-robinBDHCP relayCDefault gatewayDLoad balancer
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   Correct Answer
   D. Load balancer

   The keyed answer is "Load balancer". A load balancer distributes incoming connections across multiple servers, monitoring health and maintaining session persistence. DNS round-robin distributes queries but cannot monitor server health or manage sessions.