Network+ (PLUS) Certified Interview Questions

The CompTIA Network+ exam is a certification exam that validates the knowledge and skills required to install, configure, and troubleshoot basic networking hardware, protocols, and services. The Network+ exam objectives cover the following topics:

1.0 Networking Concepts (23%)

• Explain the purposes and uses of ports and protocols
• Explain devices, applications, protocols, and services at their appropriate OSI layers
• Compare and contrast network topologies, types, and technologies

2.0 Infrastructure (18%)

• Implement and configure wireless networks
• Install and configure switches and routers
• Implement and configure firewalls

3.0 Network Operations (17%)

• Implement network segmentation and isolation
• Identify network limitations and weaknesses
• Implement network monitoring tools and techniques

4.0 Network Security (20%)

• Explain basic concepts of network security
• Identify and mitigate network attacks and vulnerabilities
• Implement security devices and technologies

5.0 Network Troubleshooting and Tools (22%)

• Use appropriate tools to troubleshoot network problems
• Identify and troubleshoot common network connectivity issues
• Identify and troubleshoot common network service issues

Note that the percentages listed indicate the weightage of each objective in the exam.

Network+ Interview questions Domain: Networking Concepts

1. What is a network?
   Answer: A network is a group of interconnected devices that can communicate and exchange data with each other.
2. What is the purpose of a router?
   Answer: A router is a networking device that directs traffic between different networks, allowing devices on different networks to communicate with each other.
3. What is a subnet mask?
   Answer: A subnet mask is a number that defines the network portion and host portion of an IP address. It is used to determine which portion of an IP address identifies the network and which portion identifies the specific host.
4. What is the difference between TCP and UDP?
   Answer: TCP (Transmission Control Protocol) is a connection-oriented protocol that ensures reliable delivery of data. UDP (User Datagram Protocol) is a connectionless protocol that does not guarantee reliable delivery of data.
5. What is a MAC address?
   Answer: A MAC (Media Access Control) address is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network.
6. What is a DNS server?
   Answer: A DNS (Domain Name System) server is a computer server that converts domain names into IP addresses. It allows users to access websites and other resources on the internet by using human-readable domain names instead of numeric IP addresses.
7. What is a switch? Answer:
   A switch is a networking device that connects devices on a local network and allows them to communicate with each other by directing traffic between them.
8. What is a default gateway?
   Answer: A default gateway is the IP address of a router that a device uses to send traffic to destinations outside of its own network.
9. What is a VLAN?
   Answer: A VLAN (Virtual Local Area Network) is a logical grouping of devices on a network that allows network administrators to segment traffic for security, scalability, and other purposes.
10. What is a wireless access point?
    Answer: A wireless access point (WAP) is a device that allows devices to connect to a wireless network by transmitting and receiving wireless signals.
11. What is bandwidth? Answer: Bandwidth refers to the amount of data that can be transmitted over a network in a given amount of time. It is usually measured in bits per second (bps) or bytes per second (Bps).
12. What is latency?
    Answer: Latency refers to the amount of time it takes for data to travel across a network. It is usually measured in milliseconds (ms) or microseconds (µs).
13. What is a network topology?
    Answer: A network topology refers to the physical or logical layout of a network, including how devices are connected and how data flows between them.
14. What is a firewall?
    Answer: A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on a set of security rules.
15. What is NAT?
    Answer: NAT (Network Address Translation) is a technique that allows devices on a local network to share a single IP address when connecting to the internet. It translates the private IP addresses used on the local network into a public IP address that can be used on the internet.
16. What is a DMZ?
    Answer: A DMZ (Demilitarized Zone) is a separate network segment that sits between a private internal network and the public internet. It is often used to host publicly accessible services, such as web servers or email servers, while keeping the internal network secure.
17. What is a VPN?
    Answer: A VPN (Virtual Private Network) is a secure connection between two networks or devices over the internet. It allows users to access a private network from a remote location as if they were physically connected to the network.
18. What is the difference between a hub and a switch?
    Answer: A hub is a multi-port repeater, whereas a switch is a multi-port bridge. Hubs forward all traffic to all ports, while switches forward traffic only to the port where the destination device is located.
19. What is the purpose of a default gateway?
    Answer: The default gateway is the IP address of the router interface that connects to the local network. It is used as the destination IP address when a device needs to communicate with devices on other networks.
20. What is the difference between TCP and UDP?
    Answer: TCP is a connection-oriented protocol that provides reliable data transmission, while UDP is a connectionless protocol that does not guarantee reliability. TCP is used for applications that require reliable data transmission, such as email and file transfers, while UDP is used for applications that require speed and efficiency, such as streaming media and online gaming.
21. What is a VLAN?
    Answer: A VLAN is a virtual LAN that enables network administrators to segment a physical network into multiple logical networks. This allows devices that are not physically located in the same network segment to communicate with each other as if they were on the same LAN.
22. What is NAT?
    Answer: NAT stands for Network Address Translation. It is used to translate private IP addresses used on a local network to a public IP address used on the Internet. NAT allows multiple devices on a local network to share a single public IP address.
23. What is a subnet mask?
    Answer: A subnet mask is a 32-bit value used to divide an IP address into a network portion and a host portion. It is used to determine which part of an IP address is the network address and which part is the host address.
24. What is the purpose of ARP?
    Answer: ARP stands for Address Resolution Protocol. It is used to map a MAC address to an IP address, enabling devices on a local network to communicate with each other using Layer 2 addressing.
25. What is a broadcast storm?
    Answer: A broadcast storm is a network condition that occurs when a large number of broadcast packets are transmitted on a network, causing network congestion and slowing down network performance.
26. What is a gateway router?
    Answer: A gateway router is a router that connects two or more networks with different network addresses. It is used to forward packets between networks and provides a path for devices on one network to communicate with devices on another network.
27. What is the difference between a router and a switch?
    Answer: A router is a network device that connects two or more networks and forwards packets between them, while a switch is a network device that connects multiple devices on the same network and forwards packets between them. Routers operate at the network layer of the OSI model, while switches operate at the data link layer.

1. What is the difference between a hub and a switch?
   A hub is a device that forwards all incoming data to all connected devices, while a switch is a device that forwards data only to the destination device based on its MAC address.
2. What is a VLAN?
   A VLAN is a logical network that groups devices together, even if they are physically separated. VLANs can improve network security, reduce broadcast traffic, and improve network performance.
3. What is the difference between a router and a switch?
   A switch forwards data based on the MAC address, while a router forwards data based on the IP address. Routers are used to connect multiple networks together, while switches are used to connect devices within a network.
4. What is the purpose of a firewall?
   A firewall is used to protect a network from unauthorized access and attacks by monitoring and controlling incoming and outgoing network traffic based on a set of predetermined security rules.
5. What is a load balancer?
   A load balancer is a device or software that distributes incoming network traffic across multiple servers to ensure that no single server is overloaded and to improve the performance and availability of the application or service.
6. What is a VPN?
   A VPN (Virtual Private Network) is a secure connection between two or more devices or networks over the Internet. VPNs use encryption and other security measures to ensure that data transmitted over the VPN is protected from unauthorized access or interception.
7. What is the purpose of DHCP?
   DHCP (Dynamic Host Configuration Protocol) is used to automatically assign IP addresses and other network configuration information to devices on a network. This can simplify network administration and reduce the risk of IP address conflicts.
8. What is a subnet mask?
   A subnet mask is a 32-bit number that is used to divide an IP address into a network address and a host address. The subnet mask identifies which portion of the IP address is used for the network address and which portion is used for the host address.
9. What is a DNS server?
   A DNS (Domain Name System) server is used to translate domain names into IP addresses. This allows users to access websites and other resources using a human-readable name, rather than having to remember the IP address.
10. What is a proxy server?
    A proxy server is a device or software that acts as an intermediary between a client and a server. Proxy servers can be used to improve performance, filter content, or provide additional security by blocking or monitoring network traffic.

1. What is the purpose of network monitoring?
   Answer: Network monitoring is used to proactively detect and resolve network issues, identify network performance trends, monitor network security, and ensure network availability and uptime.
2. What is the difference between SNMPv2 and SNMPv3?
   Answer: SNMPv2 and SNMPv3 are both used for network management, but SNMPv3 provides better security features such as encryption, authentication, and access control.
3. What is a network protocol analyzer?
   Answer: A network protocol analyzer is a tool that captures and analyzes network traffic to help troubleshoot network issues, identify network performance issues, and detect security threats.
4. What is a Network Address Translation (NAT)?
   Answer: Network Address Translation (NAT) is a technique used to allow devices on a private network to access the internet by translating their private IP addresses into public IP addresses that can be used on the internet.
5. What is a VLAN?
   Answer: A VLAN (Virtual Local Area Network) is a logical network segment that allows network administrators to group devices together based on logical functions, project teams, or other criteria.
6. What is the purpose of a DHCP server?
   Answer: The Dynamic Host Configuration Protocol (DHCP) is used to automatically assign IP addresses to devices on a network, allowing them to connect to the network without manual configuration.
7. What is the difference between a switch and a router?
   Answer: A switch is a network device used to connect devices within a network, while a router is used to connect multiple networks together.
8. What is a subnet mask?
   Answer: A subnet mask is used to define the network and host portions of an IP address, allowing devices to communicate within a subnet.
9. What is the difference between a hub and a switch?
   Answer: A hub is a network device that connects devices together in a network, while a switch is a more advanced device that provides more features such as filtering and forwarding based on MAC addresses.
10. What is a default gateway?
    Answer: A default gateway is the IP address of the device that connects a local network to the internet, allowing devices on the network to access resources on the internet.
11. What is NetFlow and how is it used for network monitoring? Answer: NetFlow is a protocol developed by Cisco that provides network traffic visibility. It captures and analyzes data about network traffic, allowing network administrators to identify sources of congestion, monitor application performance, and detect security threats. NetFlow exports data in real-time to a network analyzer tool for further analysis and troubleshooting.
12. What is the difference between TCP and UDP? Answer: TCP (Transmission Control Protocol) is a connection-oriented protocol that ensures reliable data transmission between devices by establishing a virtual circuit before sending data. It uses sequencing and acknowledgments to ensure that packets are delivered without errors. UDP (User Datagram Protocol) is a connectionless protocol that sends data packets without establishing a connection. It does not provide error checking or sequencing, but is faster and more efficient for transmitting time-sensitive data, such as video and audio.
13. What is Quality of Service (QoS) and how is it implemented in a network? Answer: Quality of Service (QoS) is a mechanism for prioritizing network traffic to ensure that critical applications, such as voice and video, receive the necessary bandwidth and latency. QoS can be implemented by using traffic classification, traffic shaping, and traffic policing techniques. Traffic classification identifies and categorizes traffic according to priority, while traffic shaping delays or queues low-priority traffic to ensure that high-priority traffic is transmitted first. Traffic policing limits the amount of traffic that is allowed on a network link.
14. What is a Virtual Private Network (VPN) and how does it work? Answer: A Virtual Private Network (VPN) is a secure connection between two or more networks over a public network, such as the Internet. VPNs use encryption and tunneling protocols to protect data and ensure secure communication between the networks. Users can access the VPN from a remote location to connect to resources on the private network, as if they were physically on-site. VPNs can be implemented using different types of protocols, such as PPTP, L2TP/IPSec, and SSL/TLS.
15. What is a Network Address Translation (NAT) and how does it work?
    Answer: Network Address Translation (NAT) is a process that allows devices on a private network to communicate with devices on a public network, such as the Internet, by mapping private IP addresses to a public IP address. NAT is used to conserve public IP addresses, as well as provide security by hiding the private IP addresses from the public network. NAT operates by changing the source or destination IP address of IP packets that are routed through a NAT device. There are different types of NAT, such as Static NAT, Dynamic NAT, and Port Address Translation (PAT).

1. What is the difference between a firewall and an IDS/IPS? Answer: A firewall monitors and filters incoming/outgoing traffic based on predefined security rules. An IDS/IPS detects and blocks attacks in real-time based on security events it observes.
2. What is a DMZ? Answer: A DMZ (demilitarized zone) is a separate network zone that sits between a private network and the internet. It is designed to provide an additional layer of security and isolation for internet-facing services.
3. What is a VPN? Answer: A VPN (virtual private network) is a secure way to connect remote users or networks over the internet. It uses encryption and tunneling protocols to ensure secure communication.
4. What is a WAF? Answer: A WAF (web application firewall) is a type of firewall that specifically protects web applications from attacks. It filters traffic between a web server and the internet to detect and block malicious traffic.
5. What is port scanning? Answer: Port scanning is a technique used to identify open ports and services on a network. It is used by attackers to identify potential vulnerabilities in a system.
6. What is a honeypot? Answer: A honeypot is a decoy system designed to attract attackers. It is used to study and gather information about attacks, including attack techniques and patterns.
7. What is the difference between symmetric and asymmetric encryption? Answer: Symmetric encryption uses a single key to both encrypt and decrypt data, while asymmetric encryption uses a pair of keys (public and private) for encryption and decryption.
8. What is a certificate authority (CA)? Answer: A certificate authority is a trusted third-party organization that issues digital certificates used to verify the identity of a user or organization. It is commonly used for secure web browsing (HTTPS).
9. What is a DDoS attack? Answer: A DDoS (distributed denial of service) attack is an attempt to disrupt normal traffic of a targeted server or network by overwhelming it with a flood of traffic from multiple sources.
10. What is a packet sniffer? Answer: A packet sniffer is a software tool used to capture and analyze network traffic. It can be used for troubleshooting, network monitoring, and security analysis. However, it can also be used maliciously to capture sensitive data such as passwords and other confidential information.
11. What is a network segmentation and why is it important for network security?

Network segmentation is the process of dividing a network into smaller subnetworks to improve security and performance. By limiting access to sensitive data and network resources, segmentation can help prevent attackers from moving laterally throughout the network in the event of a breach. It also makes it easier to detect and respond to threats since activity within each segment is more closely monitored.

12. What is a DMZ and how is it used to enhance network security?

A DMZ (demilitarized zone) is a network segment that sits between an organization’s internal network and the internet, providing an additional layer of security. The DMZ contains servers that are accessible from the internet, such as web servers or email servers, while the internal network is kept separate and protected. This configuration allows organizations to provide public services while minimizing the potential impact of an external attack.

13. What is a honeypot and how is it used in network security?

A honeypot is a decoy system designed to lure attackers and monitor their activities. By appearing to contain valuable data or resources, a honeypot can attract attackers and provide security analysts with valuable insight into their tactics and techniques. Honeypots can be used to identify vulnerabilities in a network and provide a means of detecting and responding to attacks.

14. What is a firewall and how does it enhance network security?

A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules. Firewalls can be configured to block unauthorized access, prevent malware from entering the network, and limit the spread of malicious traffic. By enforcing a security policy at the network level, firewalls provide an essential layer of protection against a wide range of threats.

15. What is a VPN and how does it enhance network security?

A VPN (virtual private network) is a secure, encrypted connection between two or more devices over a public network, such as the internet. VPNs are used to provide remote users with secure access to internal network resources, such as file servers or databases. By encrypting traffic and authenticating users, VPNs provide a high level of security and privacy, even over untrusted networks.

16. What is port scanning and why is it used in network security?

Port scanning is the process of scanning a network to identify open ports and the services running on them. Port scanning is used in network security to identify potential vulnerabilities and to help security professionals assess the security posture of a network. Attackers may also use port scanning to identify potential targets and plan attacks.

17. What is a network intrusion detection system (NIDS) and how is it used in network security?

A network intrusion detection system (NIDS) is a security technology that monitors network traffic for signs of malicious activity. NIDS can identify suspicious patterns and anomalies in network traffic and alert security personnel to potential threats. By analyzing traffic at the network level, NIDS can detect attacks that other security technologies may miss, such as attacks on unpatched systems or zero-day exploits.

18. What is a network access control (NAC) system and how does it enhance network security?

A network access control (NAC) system is a security technology that controls access to network resources based on predefined security policies. NAC can be used to enforce security policies such as requiring anti-virus software or verifying the identity of users and devices before granting access to the network. By controlling access to the network, NAC can help prevent unauthorized access and limit the impact of security incidents.

19. What is a vulnerability scanner and how is it used in network security?

A vulnerability scanner is a security technology that identifies security vulnerabilities in network devices and software. Vulnerability scanners can be used to identify unpatched systems, misconfigured

1. What is the purpose of a cable tester in network troubleshooting?
   Answer: A cable tester is used to test and verify the physical connectivity of network cabling, such as twisted-pair copper cables. It checks for continuity, shorts, and open circuits.
2. What is the difference between a protocol analyzer and a packet sniffer?
   Answer: A protocol analyzer is a network tool used to capture, analyze, and decode network traffic to diagnose issues or optimize network performance. A packet sniffer is a tool that intercepts and captures network traffic, and can be used for troubleshooting or monitoring network activity.
3. What is the purpose of a loopback adapter in network troubleshooting?
   Answer: A loopback adapter is a hardware device used to test the functionality of a network interface card (NIC) by sending packets to itself. It can be used to isolate issues with the NIC or network configuration.
4. What is the ping command used for in network troubleshooting?
   Answer: The ping command is used to test the connectivity between two network devices by sending an Internet Control Message Protocol (ICMP) echo request and waiting for an ICMP echo reply. It can be used to verify the connectivity of a host, identify packet loss, and determine network latency.
5. What is a traceroute command used for in network troubleshooting?
   Answer: The traceroute command is used to trace the path that packets take from one network device to another. It shows the network hops between devices and can be used to identify connectivity issues, such as packet loss or high latency.
6. What is the purpose of a toner probe in network troubleshooting?
   Answer: A toner probe is a tool used to identify the physical location of a network cable in a building or wiring closet. It can be used to locate a specific cable among many cables and verify the correct cable is connected to a specific port.
7. What is the purpose of a cable certifier in network troubleshooting?
   Answer: A cable certifier is a tool used to test and verify the performance of network cabling, such as twisted-pair copper cables. It checks for errors, attenuation, and crosstalk, and can provide a detailed report of cable quality and performance.
8. What is the difference between a continuity tester and a cable tester?
   Answer: A continuity tester is used to verify that a circuit or wire is continuous, with no breaks or interruptions. A cable tester is used to test and verify the physical connectivity of network cabling, including continuity as well as shorts and open circuits.
9. What is the purpose of a protocol analyzer filter in network troubleshooting?
   Answer: A protocol analyzer filter is used to capture and analyze specific network traffic based on criteria such as IP addresses, protocols, or ports. It can help narrow down the focus of analysis and identify specific issues or performance bottlenecks.
10. What is a port scanner used for in network troubleshooting?
    Answer: A port scanner is used to identify open ports on a network device, such as a firewall or server. It can be used to identify potential security vulnerabilities or verify that a service is available on a specific port.
11. What is a protocol analyzer and how can it be used for network troubleshooting?
    Answer: A protocol analyzer is a tool that captures and analyzes network traffic. It can be used for troubleshooting network issues by capturing and analyzing packets to identify issues with network protocols, devices, or configurations.
12. What is a network scanner and how can it be used for network troubleshooting?
    Answer: A network scanner is a tool that scans a network to identify devices, open ports, and vulnerabilities. It can be used for troubleshooting network issues by identifying network topology, potential security threats, and identifying misconfigured devices.
13. What is a ping tool and how can it be used for network troubleshooting?
    Answer: Ping is a tool that sends ICMP packets to a network device to test its connectivity and measure its response time. It can be used for troubleshooting network connectivity issues by verifying network reachability and identifying network latency issues.
14. What is a traceroute tool and how can it be used for network troubleshooting?
    Answer: Traceroute is a tool that traces the path of packets across a network to identify network hops and measure their response time. It can be used for troubleshooting network issues by identifying network bottlenecks, routing issues, and connectivity problems.
15. What is a cable tester and how can it be used for network troubleshooting?
    Answer: A cable tester is a tool that verifies the integrity of network cables by testing for continuity, open circuits, and shorts. It can be used for troubleshooting network issues by identifying cable faults, miswiring, and cable length limitations.
16. What is a loopback adapter and how can it be used for network troubleshooting?
    Answer: A loopback adapter is a virtual network adapter that allows a device to send and receive packets to itself. It can be used for troubleshooting network issues by testing network interface functionality and identifying issues with network drivers or configuration settings.
17. What is a multimeter and how can it be used for network troubleshooting?
    Answer: A multimeter is a tool that measures electrical voltage, current, and resistance. It can be used for troubleshooting network issues by verifying power supply and identifying issues with network equipment or cabling.
18. What is a syslog server and how can it be used for network troubleshooting?
    Answer: A syslog server is a tool that collects and analyzes log messages from network devices. It can be used for troubleshooting network issues by identifying error messages, security threats, and performance issues on network devices.
19. What is a SNMP tool and how can it be used for network troubleshooting?
    Answer: SNMP (Simple Network Management Protocol) is a protocol used to manage network devices. SNMP tools can be used for troubleshooting network issues by monitoring network device status, performance, and configuration settings.
20. What is a network analyzer and how can it be used for network troubleshooting?
    Answer: A network analyzer is a tool that captures and analyzes network traffic at a high level. It can be used for troubleshooting network issues by identifying network protocols, analyzing network traffic patterns, and identifying security threats.