30+ Interview Question and answers for Network Engineer

In this article, we have listed Interview Questions and Answers for Network Engineer Job opportunities. These Network Engineer Interview Question Answers are divided into various categories which will help you crack Interviews and secure your job. All the categories and questions are listed below, click and explore the l/topic -

Interview Questions for Network Engineer Categories:

Basic Questions

Beginner network engineer interview questions

Intermediate Network Engineer Interview Questions

Advanced network engineer interview questions

Conclusion

Paid Network Engineer Interview Questions and Answers

Free Network  Engineer Interview Questions and Answers

Basic Questions:

1. What are the different types of networks?

Answer:

• LAN (Local Area Network) – Covers a small area (e.g., office, home).

• WAN (Wide Area Network) – Covers large geographical areas (e.g., Internet).

• MAN (Metropolitan Area Network) – Covers a city or large campus.

• PAN (Personal Area Network) – Bluetooth, IoT connections.

• SAN (Storage Area Network) – Dedicated high-speed network for storage.

2. What is the difference between a hub, switch, and router?

3. What is the OSI model? Can you explain each layer?

Answer: OSI (Open Systems Interconnection) model has 7 layers:

1. Physical – Hardware (cables, switches, fiber optics).

2. Data Link – MAC addresses, Ethernet, ARP.

3. Network – Routing, IP addresses, subnetting.

4. Transport – TCP/UDP, port numbers, reliability.

5. Session – Manages communication sessions (authentication, APIs).

6. Presentation – Data encryption, compression, formats (SSL, ASCII).

7. Application – End-user apps (HTTP, FTP, DNS, SMTP).

4. What is TCP/IP, and how does it differ from the OSI model?

Answer: TCP/IP is a 4-layer model used for networking:

Unlike OSI, TCP/IP is practical and widely used in real-world networks.

5. What is subnetting, and why is it important?

Answer:

• Subnetting divides a large network into smaller sub-networks.

• Improves security, network efficiency, and performance.

• Reduces IP address waste.

Example:For a /24 subnet (255.255.255.0), the network can have 256 IPs (0-255), but only 254 are usable (excluding network and broadcast addresses).

6. What is the difference between IPv4 and IPv6?

7. What is NAT (Network Address Translation)?

Answer:

• NAT allows multiple devices on a local network to use a single public IP for Internet access.

• Helps in IP address conservation and security.

• Types:

  • Static NAT – One-to-one mapping (private to public IP).

  • Dynamic NAT – Assigns a public IP from a pool.

  • PAT (Port Address Translation) – Multiple private IPs share one public IP (used in homes & offices).

8. What are VLANs (Virtual Local Area Networks)?

Answer:

• VLANs segregate network traffic logically without needing separate physical switches.

• Improves security, efficiency, and performance.

• Example: VLAN 10 (HR), VLAN 20 (Finance), VLAN 30 (IT).

• Uses 802.1Q tagging for VLAN communication across switches.

9. What is the difference between TCP and UDP?

10. What are routing protocols, and how do they work?

Answer: Routing protocols help routers determine the best path for forwarding packets.

• Static Routing – Manually configured.

• Dynamic Routing – Automatically updates routes based on network changes.

Types of Dynamic Routing Protocols:

• Distance Vector – RIP (Routing Information Protocol).

• Link-State – OSPF (Open Shortest Path First).

• Hybrid – EIGRP (Enhanced Interior Gateway Routing Protocol).

11. What is BGP (Border Gateway Protocol)?

Answer:

• BGP is an exterior gateway protocol used for routing between autonomous systems (AS) on the Internet.

• Uses path vector routing based on AS paths.

• Ensures Internet routing stability (used by ISPs, large networks).

12. What are firewalls, and how do they work?

Answer:

• Firewalls filter network traffic based on security rules.

• Types:

  • Packet Filtering Firewall – Checks IP addresses & ports.

  • Stateful Firewall – Tracks active connections.

  • Application Firewall – Inspects application-layer traffic (e.g., Web Application Firewall - WAF).

13. What is a VPN (Virtual Private Network), and how does it work?

Answer:

• VPN encrypts internet traffic between a user and a private network.

• Ensures secure remote access to a corporate network.

• Types:

  • SSL VPN – Uses HTTPS (for web-based access).

  • IPSec VPN – Secure Layer 3 VPN used in enterprises.

14. What is SDN (Software-Defined Networking)?

Answer:

• Decouples network control (control plane) from forwarding hardware (data plane).

• Uses centralized controllers (e.g., OpenFlow, Cisco ACI).

• Improves network flexibility, automation, and scalability.

15. What is Network Automation, and why is it important?

Answer:

• Uses scripts & tools to automate network configuration.

• Reduces manual errors, improves efficiency, and speeds up deployment.

• Tools:

  • Ansible, Python, Terraform for network automation.

  • Cisco DNA, Juniper Contrail for SDN.

16. How does Wi-Fi work? What is the difference between 2.4GHz and 5GHz?

Answer:

• Wi-Fi uses radio waves to transmit data between devices and an access point.

• 2.4 GHz – Covers longer distance but slower speed.

• 5 GHz – Faster speed but shorter range (better for HD streaming).

17. How do you troubleshoot a slow network?

Answer:

1. Check device connectivity (ping, traceroute).

2. Analyze network traffic (Wireshark, NetFlow).

3. Check for packet loss & latency (MTR, ping test).

4. Verify DNS and DHCP settings.

5. Check for network congestion (bandwidth monitoring tools).

18. Why do you want to be a Network Engineer?

Answer: "I enjoy working with networking technologies, solving connectivity challenges, and optimizing network performance. I am passionate about network security, automation, and cloud networking, and I want to contribute to building reliable and efficient networks."

Beginner network engineer interview questions:

The network engineer interview questions for beginners are given below:

1.What do you mean by a network?

A: A network can be considered as a set of devices of systems that are connected.They can communicate and share information. Devices such as computers, laptops, servers, and printers can be connected through networks like LAN (Local Area Network) and WAN (Wide Area Network).

2.What is a link?

A. A connection between two or more devices is called a link. A link defines different protocols that help a device to connect with another device within a network.

3.What do you mean by a node?

A:

• A node is a point where two or more devices connect within a network.

• A node is where data is received, stored, sent and created within the network.

• Nodes can be an endpoint for transmitting data or a redistribution point. Any device connected to another device inside a network is a node itself.

• Common examples of nodes are switches, routers, bridges, and servers, which may be connected or other devices through the internet.

4.What is a router?

A. 

• A router is a physical device that is used for receiving, storing, analyzing and forwarding data packets to other nodes inside or outside the network.

• Routers can connect to devices such as a modem, optic fiber and a cable to connect and share information between devices.

• Routers contain firmware and software. Firewalls are installed in routers for securing the network.

• Moreover, routers use forwarding tables and headers for determining the best path for transferring the data packets.

5.Can you define the OSI model?

A. 

• The OSI (Open System Interconnection) is a reference model that has the necessary protocols and standards for communicating over a network.

• The model was made by the International Organization for Standardization (ISO) in 1984. It consists of seven layers, where each layer has a different function.

• These layers are Physical Layer, Data Link Layer, Network Layer, Transport Layer, Session Layer, Presentation Layer, and Application Layer.

6.What is the TCP IP model in networking?

A. The TCP IP (Transmission Control Protocol and Internet Protocol) model is a more precise representation of the OSI model.

The current architecture of the internet is based on the TCP IP model. It was developed by the Department of Defence's Project Research Agency as a part of their project for communication within systems and remote machines.

It has 4 layers that have protocols required for communication between devices of a network. They are as follows:

• Application Layer (Process layer)

• Transport Layer (Host-to-Host layer)

• Internet Layer

• Link Layer (Network Access)

7.What do you mean by a point to point link?

A.

• A point to point link is a connection between two dedicated networking devices.

• The complete bandwidth of the link is utilized for the transmission of data between two devices.

• There may be multiple connections between devices. Using a PPP link, two different networks can be connected, where one network will work as the endpoint for another.

• These days PPP links are created using modems and PSTN (Public Switched Telephone Networks).

• An example of a PPP link is a telephone call between two people.

8.Can you state the differences between a switch, router, and a hub?

A. 

• A switch is used for forwarding the data packets in a network. It facilitates error checking for the data packets and sends error-free packets to the destined ports properly.

• A router is a networking device that transfers data packets after analyzing their contents.

• The correct destination, correctness and IP address of the data packets are checked by the router.

• They make use of a routing table for finding out the best path for transmission.

• A hub is a connection point for networking devices. Different segments of a LAN are connected using a LAN. It also has several ports for communication.

• If a packet arrives at a hub port, it is copied to the other ports so that it is visible to the other segments of the LAN. But as they are unable to filter data, it sends the data packets to all the connected devices.

9.What do you mean by a backbone network?

A. 

• A backbone network is a network that has the connectivity infrastructure that is the main link for the various parts of a network.

• It has the capability of supporting networks spread over vast geographical areas.

• It can connect different networks within the same area or building, or different buildings within an area.

• Typically, a backbone network comprises routers, bridges, gateways, and switches.

10. Define subnet mask?

A. 

• A subnet mask is a number that specifies the range of IP addresses that are available in a network.

• A subnet mask puts a limit on the number of valid IP addresses. This is the 32-bit number that is used for masking the IP address.

• Subnet mask divides the IP address into a host address and network address.

• Two or more systems within the same subnet can communicate with each other. If a system is connected to a network, its subnet mask can be determined by accessing the Network Control Panel.

Intermediate Network Engineer Interview Questions:

The intermediate network engineer/NOC engineer interview questions are given below:

1.What is a DNS?

A. 

• DNS stands for domain name system. Websites are accessed by their domain names such as google.com and yahoo.com. But these names are not understood by the computer.

• The DNS translates these names into IP addresses so that the browsers can load them for the users.

• DNS converts the hostname of the website into an IP address that is readable by the computer.

• The conversion of hostnames into IP addresses is called forward lookup. Converting or resolving IP addresses into hostnames is called backward lookup.

2. Can you define NAT?

A.

• NAT stands for Network Address Translation. This is for IP networks that are using unregistered IP addresses.

• NAT enables them to connect to the internet. In this process, a public address is assigned to a system within a private network.

• NAT operates using a router and converts the private addresses into legal addresses.

• It is also used for securing networks by limiting the number of IP addresses a company can use within a network.

3. Mention the different types of LAN cables used in networking. What do you mean by a cross cable?

A. Some of the common types of LAN cables that are used in networking are CAT 5 and CAT 6. CAT 5 provides 100 Mbps of speed and CAT 6 offers 1 Gbps of speed.

However, the three major types of network cables are coaxial, fiber optic and twisted pair.

A cross cable is also called a crossover cable that is used for connecting two similar devices for communication without the help of a hub or a switch.

4. What is the use of a proxy server?

A.

• Proxy servers are used for securing a network from external users who might want to intrude into the network. It makes a computer system virtually invisible to others.

• A proxy server has a list of harmful websites so that the main network is protected.

• When it receives a request, it collects the data from the target web server and processes it. The response is then forwarded to the user.

5. What do you understand by domain and workgroup?

A.

• Domain is a group of computers in a network, which are connected. The members of a domain consist of users, workstations and database servers.

• Devices within the same domain are administered using the same protocols and rules.

• When an active directory is installed, a domain is created. Domains can be used for administering computers centrally, which is not possible in a workgroup.

• A workgroup is a set of connected computers that share resources. Here, all the computers are peers and they do not have control over one another. All peers must be on the same LAN and subnet.

6.What is 127.0.0.1?

A.

• The IP address 127.0.0.1 is a reserved address that is used for localhost connections.

• It is a special IPv4 address that is also called a loopback address. It is not a real IP address but all systems have this address which means “this computer”.

• During any connection issues, the server is pinged to check whether it is responding with the help of this address. The address is only used by the computer you are currently working on.

7.Can you differentiate between the internet, intranet, and extranet?

A.

• The internet is a global network that connects thousands of computers. Information can be accessed and shared from any location that has access to the internet.

• An intranet is a network that is unique to a firm where data is accessed and shared among the computers within that network only.

• An extranet is a network where only specific members are allowed access. These may include vendors, customers, suppliers, and other officials who are associated with a company.

• The extranet handles the secure part of the website that is accessed through IDs and passwords.

8.What is the active directory?

A. An active directory provides ways to handle the relationships and identities within a network. It allows the network administrator to manage domains, objects, and users in a network.

The admin can create a user group and assign special access privileges to them for accessing specific directories on the server.

The 3 main components of the active directory structure are

• Domain

• Trees

• Forests

9.What is FTP and anonymous FTP?

A. FTP stands for file transfer protocol. This is used by the TCP/IP model for transferring files from a host system to another host system.

It is used for downloading files from the server to a computer and transferring web pages very efficiently.

Anonymous FTP is a method of providing access to certain public servers. Users who have been granted access to these servers do not need identification, instead, they can just log in as guests.

Advanced network engineer interview questions:

Below is a list of Network Engineer Interview Questions that are of advanced level.

1.What is the difference between ipconfig and ifconfig commands?

A.The ipconfig command stands for Internet protocol configuration that is used for configuring networking devices on Windows machines.

All the TCP/IP network summary data can be displayed through this command using the command line.

It is also used for refreshing the settings of Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS).

The ifconfig stands for interface configuration. The command is used for configuring and managing the network interface parameters on the TCP/IP network.

The network interface IP addresses can be viewed with the help of this command. The command is used on MAC, LINUX and Unix operating systems.

2.What do you understand about DHCP?

A.DHCP stands for Dynamic Host Configuration Protocol. This protocol assigns IP addresses and network configuration parameters to devices within a network.

It helps the devices to communicate with each other and reduces the problems caused due to the allocation of IP addresses manually.

DHCP allocates addresses from its pool of IP addresses to network devices.

The protocol initially checks whether the next available address is assigned to a device. If not, it allocates a device to this IP address.

3.What is Netstat?

A.Netstat stands for network statistics. It is a network utility of the command line.

This command is used for displaying information about the TCP/IP settings, incoming and outgoing connections, network protocol statistics and routing tables.

The command is used on Windows and Unix operating systems. Netstat is useful for determining the network traffic and problems in the network.

On a Windows system, the command netstat can be entered in the command line. You will see a list of all active network connections.

4.What is the importance of APIPA in networking?

A.APIPA stands for Automatic Private IP Addressing. This is an important feature of Windows systems that allow the device to assign an IP address to itself when there is no DHCP.

This IP address has a range of 169.254.0.1 through 169.254.255.254. Any client system can use this APIPA address until the DHCP server is available.

This facility is commonly used for small organizations having about 25 clients.

5.What is SMTP?

A.

• SMTP stands for Simple Mail Transfer Protocol. This protocol is used for delivering emails over a network from one system to another.

• It is a part of the TCP/IP application layer protocol that uses a method called “store and forward”.

• This is used for sending emails across the networks with the help of a Mail Transfer Agent.

• SMPTP can send messages to one or more clients within or outside the network. These messages can include text, voice, images or graphics.

6.What do you mean by NIC?

A.

• NIC stands for Network Interface Card, also called an Ethernet card or a network adapter.

• This is a hardware component that is essential for connecting the computer to a network.

• NIC is a card that is installed in a system for connecting to the internet. This is important for wireless, wired and LAN communication.

• It has a unique MAC address that will help in identifying the computer within a network.

7.How would you define CSMA/ CD?

A. 

• CSMA/ CD stands for Carrier-sense multiple access Collision Detection. This protocol defines the way two devices interact when a data collision occurs.

• The protocol has rules of how long the devices in a network must wait when a collision happens.

• It analyses if the communication channel is busy or not, and controls the transmission accordingly.

• If it detects a collision, the transmission of the station is stopped. It then sends a jam signal and waits for some time before transmitting again.

8.What is the use of a VPN?

A.

• VPN stands for Virtual Private Network that can be considered as a private Wide Area Network.

• This network protects anonymity while surfing the internet and accessing certain websites that might be potentially dangerous.

• It is used in corporate environments where a computer may be connected to a remote server.

• Traffic on a VPN is sent by creating an encrypted connection over the internet called a tunnel. This provides unauthorized access and eavesdropping over the network.

9.What is a MAC address?

A.

• A MAC (Media Access Control) address is used for uniquely identifying a device on a network.

• Also called the physical address or ethernet address, MAC addresses are 48-bit numbers that are present in the NIC of the devices.

• This is an address given by the manufacturer of the device. The MAC sub-layer of the data link layer makes use of the MAC addresses.

• They are 12-digit hexadecimal numbers, where the first 6 digits identify the manufacturer.

10.Can you define OSPF?

A. OSPF stands for Open Shortest Path First. This is a link-state routing protocol that is used for identifying the best path for transferring data packets.

This protocol is useful as it makes use of the network bandwidth efficiently.

11.What is a tracert command?

A.The tracert command is used for displaying information about the path taken by a data packet to reach the destination network from the router.

The total number of hops taken by the packet during the transmission is also displayed.

Conclusion:

Before going for the interview, make sure that you brush up your basics about the field and are well-versed with the basic terms.

Read up about the new technologies that may affect the network engineering scenario to answer better.

Paid Network Engineer Interview Questions and Answers:

Free Network  Engineer Interview Questions and Answers: