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CompTIA Network+ (N10-009): Practice Questions
Original practice questions for CompTIA Network+ (N10-009), with explanations of why each answer is right and the others wrong. Filter by domain or difficulty. These are concept and scenario checks - not real exam questions.
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Which OSI layer handles logical addressing (IP addresses)?
Correct answer: D. Layer 3 (Network) handles logical addressing and routing with IP. Layer 2 uses MAC addresses; Layer 4 uses ports; Layer 7 is application protocols. -
Which port does HTTPS use by default?
Correct answer: A. HTTPS uses TCP 443. Port 80 is HTTP, 22 is SSH, and 53 is DNS. -
Which protocol resolves domain names to IP addresses?
Correct answer: B. DNS maps names to IP addresses. DHCP assigns addresses; NTP synchronises time; SNMP monitors devices. -
A /26 subnet provides how many usable host addresses per subnet?
Correct answer: B. A /26 has 64 total addresses minus network and broadcast, leaving 62 usable. 64 is the total; 30 is a /27; 126 is a /25. -
Which device operates at Layer 3 and forwards traffic between networks?
Correct answer: C. A router forwards between networks using IP at Layer 3. Hubs and repeaters are Layer 1; a standard switch is Layer 2. -
The 802.11 family of standards refers to:
Correct answer: A. 802.11 defines wireless LAN (Wi-Fi) standards. Fiber, copper cabling categories and VPNs are covered by other standards. -
A host's default gateway is:
Correct answer: D. The default gateway is the router a host sends traffic to for destinations outside its subnet. It is not the DNS server, the DHCP scope, or the broadcast address. -
SNMP is primarily used to:
Correct answer: A. SNMP collects metrics and manages network devices. Encryption, addressing and name resolution are handled by other protocols. -
Which most improves network high availability?
Correct answer: D. Redundancy with failover keeps the network running when a component fails. Single points of failure reduce availability; disabling logging and longer cables do not help. -
An up-to-date network diagram primarily helps with:
Correct answer: D. Diagrams document the network and speed up troubleshooting. They do not encrypt, add bandwidth, or assign addresses. -
A firewall primarily:
Correct answer: C. A firewall permits or denies traffic by rule. Addressing, name resolution and bandwidth are unrelated functions. -
A VPN provides:
Correct answer: C. A VPN encrypts traffic between endpoints across an untrusted network. It does not inherently speed routing, add addresses, or cache DNS. -
Which switch feature mitigates a rogue DHCP server?
Correct answer: A. DHCP snooping trusts only authorised DHCP ports, blocking rogue servers. STP prevents loops; NAT translates addresses; QoS prioritises traffic. -
Which command tests basic reachability to a host?
Correct answer: B. ping sends ICMP echo requests to test reachability. format, chmod and grep are unrelated operating-system commands. -
The first step of a structured troubleshooting methodology is to:
Correct answer: B. You identify the problem first, then theorise, test, implement and document. Implementing or escalating before identifying the issue is premature. -
High latency and jitter most degrade which type of application?
Correct answer: D. Real-time media like VoIP and video are very sensitive to latency and jitter. Email, archival and backups tolerate delay far better. -
TCP operates at which OSI layer?
Correct answer: C. TCP is a Layer 4 transport protocol. Layer 3 routes, Layer 2 frames, and Layer 7 is applications. -
Which port does DNS use by default?
Correct answer: B. DNS uses port 53. Port 80 is HTTP, 443 is HTTPS, and 25 is SMTP. -
Compared with TCP, UDP is:
Correct answer: D. UDP is connectionless and lightweight, trading guaranteed delivery for speed. 'Always reliable and acknowledged' describes TCP, not UDP; 'always encrypted' and 'without any ports' are both false (UDP is unencrypted and does use port numbers). -
A MAC address operates at which layer?
Correct answer: A. MAC addressing is a Layer 2 function. IP is Layer 3; ports are Layer 4; apps are Layer 7. -
A straight-through Ethernet cable is traditionally used to connect:
Correct answer: D. A straight-through cable traditionally connects unlike devices such as a PC to a switch; crossover cables joined like devices before auto-MDIX. Connecting two PCs directly or two routers' serial ports needs different cabling, and a device cannot be cabled to itself this way. -
Compared with 2.4 GHz, the 5 GHz Wi-Fi band generally offers:
Correct answer: A. 5 GHz offers higher speeds but shorter range and weaker wall penetration than 2.4 GHz. 'Longer range but lower speed' describes 2.4 GHz instead; 'no difference' and 'zero interference always' are both false. -
A VLAN logically:
Correct answer: A. VLANs segment a switch into separate broadcast domains. They do not encrypt, assign public IPs or replace routing. -
SNMP traps are:
Correct answer: C. SNMP traps are unsolicited alerts a device sends to its management system when an event occurs. They are not DNS records, routing updates or encryption keys, which are handled by entirely different mechanisms. -
Quality of Service (QoS) is used to:
Correct answer: A. Quality of Service prioritizes time-sensitive traffic such as voice and video so it is not delayed. Encrypting data, assigning MAC addresses and scanning for open ports are unrelated functions handled by other technologies. -
A high-availability network design typically uses:
Correct answer: D. Redundancy and failover keep the network up. The single-point options reduce availability. -
A screened subnet (DMZ) is used to:
Correct answer: D. A screened subnet (DMZ) hosts public-facing services while isolating the internal network behind it. It does not replace the firewall, store long-term backups, or speed up DNS; those are separate roles. -
802.1X provides:
Correct answer: C. 802.1X provides port-based access control, authenticating a device or user before granting network access. It does not perform DNS resolution or IP addressing, and it is not limited to wireless encryption. -
Which command shows the path packets take to a destination?
Correct answer: A. Traceroute lists each hop to the target. Ping tests reachability, ipconfig shows local settings, and nslookup queries DNS. -
A user can reach websites by IP address but not by name. The most likely problem is:
Correct answer: B. Working IP but failing names points to DNS. The hardware items would not cause this specific symptom.
Practice questions FAQ
- Are these real N10-009 exam questions?
- No. These are original study questions written to test understanding. They are not real exam questions, exam dumps, or copied from any provider.
- How should I use these practice questions?
- Answer each one, read the explanation (including why the wrong options are wrong), and use the per-domain score below to focus your revision on weak areas. Revisit before exam day.
- How many questions should I do before the exam?
- Enough to score consistently across every domain, alongside full-length practice from official or reputable providers. Understanding why each answer is right matters more than raw volume.
- What score means I am ready?
- A good signal is consistently scoring around 80% or higher across all domains on questions you have not seen before, and being able to explain why the wrong options are wrong.
- Should I use exam dumps?
- No. Dumps (real or leaked questions) breach provider policy, can void your certification, and do not build the understanding the exam actually tests.