PrepFree Network+ practice test
12 original questions written by our editors against the official CompTIA exam domains. They are not real exam questions. Pick an answer to see why it is right or wrong.
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Question 1 of 12Networking concepts
A new office floor needs one subnet for 50 hosts. The network team wants to use the smallest IPv4 subnet that still fits all of them. Which prefix should they use?
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Answer: B. A /26 gives 64 addresses and 62 usable hosts, the smallest size that fits 50. A /27 gives only 30 usable hosts and a /28 only 14, so both are too small. A /25 (126 usable) would work but wastes addresses.
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Question 2 of 12Networking concepts
A company streams a live training video to about 200 employees on its LAN. The current setup sends a separate copy of the stream to each viewer and is overloading the links. Which delivery method sends one stream that only subscribed hosts receive?
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Answer: B. Multicast sends one stream to a group address, and only hosts that join the group receive it. Unicast is the current one-copy-per-viewer problem, and broadcast would hit every host on the segment whether it wants the stream or not. Anycast delivers to the nearest single member of a group, which suits services like DNS, not streaming to many viewers.
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Question 3 of 12Networking concepts
An auditor finds that switches are managed over a protocol that sends usernames and passwords in clear text. The team must keep command-line management but encrypt the session. Which protocol and default port should they use?
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Answer: D. SSH provides an encrypted command-line session and uses TCP port 22 by default. Telnet is the clear-text protocol the auditor flagged. TFTP is for unauthenticated file transfer, and SNMPv2c is a monitoring protocol whose community strings are also sent in clear text.
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Question 4 of 12Network implementation
Two access switches are joined by a single cable. Users in VLAN 10 and VLAN 20 are on both switches and must reach others in their own VLAN across that link. How should the link ports be configured?
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Answer: C. An 802.1Q trunk tags frames with their VLAN ID so several VLANs can share one physical link. An access port carries only one VLAN, so VLAN 20 traffic would not cross. Port mirroring copies traffic for analysis, and link aggregation bundles multiple links for bandwidth without solving the multi-VLAN problem.
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Question 5 of 12Network implementation
An open-plan office has three 2.4 GHz access points close to each other. Users report slow Wi-Fi, and a survey shows heavy interference between the APs. Which channel plan best reduces the problem?
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Answer: B. In the 2.4 GHz band, channels 1, 6 and 11 do not overlap, so neighbouring APs on them do not interfere with each other. Putting all APs on one channel creates co-channel contention, and channels 1, 2 and 3 heavily overlap. Raising power increases the overlap and makes interference worse.
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Question 6 of 12Network operations
After a firewall upgrade, a manager asks whether 70% utilization on the internet link at 10:00 is unusual. The team has no way to answer. What should they have created before the change?
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Answer: A. A baseline records normal performance over time, so current readings can be compared against it. A physical diagram shows cabling and device locations, not traffic levels. An SLA sets the ISP's commitments, and a change request documents approval, but neither tells you what normal utilization looks like.
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Question 7 of 12Network operations
A retailer's disaster recovery plan states that, after a failure, the order database must lose no more than 15 minutes of transactions. Which metric does this requirement define?
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Answer: A. RPO is the maximum acceptable amount of data loss, measured back in time from the failure, so it drives backup or replication frequency. RTO is how quickly service must be restored. MTBF and MTTR describe reliability and repair speed, not acceptable data loss.
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Question 8 of 12Network security
A clinic offers guest Wi-Fi in its waiting room. Guests must get internet access but must never reach the internal patient records server. What is the most effective control?
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Answer: A. Network segmentation with a dedicated guest VLAN and ACLs enforces that guest traffic can only go to the internet. Hiding the SSID does not stop connected guests from reaching internal systems. MAC filtering is easy to spoof and protects the wrong network, and a longer key only controls who joins, not where they can go.
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Question 9 of 12Network security
Several PCs suddenly receive a wrong default gateway. The team finds a small router someone plugged into a wall port that is handing out IP addresses. Which switch feature would have blocked its DHCP offers?
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Answer: C. DHCP snooping marks only approved ports as trusted for DHCP server messages and drops offers from untrusted ports. Dynamic ARP inspection stops ARP spoofing, not rogue DHCP offers. Port mirroring only copies traffic, and BPDU guard shuts ports that send spanning tree BPDUs, which a rogue DHCP server need not do.
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Question 10 of 12Network troubleshooting
A user cannot reach any network resource. Running ipconfig shows the address 169.254.33.10 with a 255.255.0.0 mask and no default gateway. What is the most likely cause?
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Answer: D. A 169.254.x.x address is an APIPA (link-local) address that Windows assigns itself when no DHCP server answers. A DNS fault would not change the IP address, and a duplicate static IP would show the configured address with a conflict warning. A failed gateway would still leave a DHCP-assigned address in place.
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Question 11 of 12Network troubleshooting
Users can reach an internal web server by typing its IP address, but typing intranet.example.local returns an error. Pinging the server by IP works. Which service should the technician check first?
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Answer: C. Access by IP works but access by name fails, which points to name resolution, the job of DNS. DHCP problems would stop IP connectivity altogether. NTP keeps clocks in sync and SNMP is for monitoring; neither turns names into addresses.
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Question 12 of 12Network troubleshooting
An older server's network performance is very poor. The switch port connected to it shows a rising count of late collisions, and the server's NIC reports CRC errors. Cabling tests pass. What is the most likely cause?
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Answer: D. Late collisions on one side and CRC errors on the other are the classic sign of one end running half duplex and the other full duplex. A wrong VLAN would cause no connectivity, not interface errors. MTU problems cause fragmentation or dropped large packets, and an IP conflict causes intermittent reachability, not layer 1/2 error counters.
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