Network Security Interview Questions and Answers [Complete List] 

Are you considering a career as a Network Engineer? Are you thinking of quitting your current career and starting a new networking job at a different company? Has it been a while since you interviewed for a career as a network engineer?


Continue reading if you responded yes to any of these questions. We've put up a list of Network Security Interview Questions as well as some recommendations for acing the interview.

Tips before your Interview as a Network Security Engineer

1. Open the books and give yourself a broad overview of networking before going to your interview. Go as far as you can with your research and familiarize yourself with the topics you're unfamiliar with.


2. Refresh your resume. Examine your resume and make any necessary changes. When you're putting your best foot forward, the last thing you need is a resume that's full of grammatical mistakes. 


Furthermore, LinkedIn is an excellent platform for showcasing your abilities and expertise; don't overlook this tool's global reach.


3. Obtain Certification - Obtaining a certification is one of the finest ways to demonstrate that you know what you're talking about. This allows a potential employer to quickly assess your expertise level.


4. Many companies are becoming increasingly astute and will conduct a social media search for your name. Make sure there isn't anything offensive on your Twitter/Facebook/Instagram profile in case they locate it.


5. Keep an eye out for social media sites. Know the company you’ve applied for.


6. Google yourself to make sure that you did not share information that you do not want to be reviewed by the company. 

What is the Main Goal of Network Security?

In today's world, businesses rely heavily on computer networks to efficiently and effectively transmit information throughout the corporation.


Organizational computer networks are getting increasingly massive and widespread. Assuming that each employee gets their own workstation, a major corporation would have thousands of workstations and several servers.


These devices are unlikely to be remotely managed or protected from the outside world. They may employ a variety of operating systems, hardware, software, and protocols, and their users may have varying levels of cyber awareness.


Imagine if thousands of workstations on your company's network are linked to the Internet directly. This type of unprotected network becomes a target for an attack since it contains important information and has flaws.


In the following points, we will discuss the most important network security terminologies shedding the light on the network security fundamentals you should never miss. 

Network Security Interview Questions and Answers

1. Brief of Seven Layers of OSI Model

Being familiar with OSI Model is a must in any network security interview questions. 


1) The Physical Layer is the lower OSI model layer that deals with raw pre-structured data typically zeros and ones (01)  that are transmitted optically (fibers) or electrically through physical cables. 


2) Data Link Layer is the second-lowest layer where data starts to take the path to the destination from starting node to destination node encapsulating these data to frames. 


3) The Transport Layer has many functionalities regarding data transmission: 

- Control flow: organizing the flow rate of data by sending data at the same rate matching the connection speed of receiving data.

- Error Control: Check that data is properly received, if not; request it again. (By ack value)

- TCP/UDP protocols headers are added to the packet received for the lower network layer to construct segments (transport data representation).

4) Network Layer has the main function of receiving frames that are structured in the data link layer, then delivering them to their destinations based on the addresses inside the frame headers. 


5) Session Layer creates communication sessions. 


- Communication between two devices requires synchronized sessions on both devices; a channel between the sessions on two devices should be open. 

- Sessions are synchronized by checkpoints if the communication is interrupted by any means, the sessions restore the last checkpoint to recover status and resume transferring data in a correct sequence

6) Presentation Layer transforms data from a form that is transmittable in the lower layers to a readable form to prepare it for the upper application layer.


7) Application Layer is the final layer that is manipulated by the end-user software such: as web browsers called user agents such as (firefox, chrome, safari) and email clients such (as Mozilla Thunderbird, Microsoft Outlook, Apple Mail).

2. What is Cross-site Scripting?

Cross-Site Scripting (XSS) is a type of client-side injection attack that involves injecting malicious code into a victim's web browser to execute malicious scripts.


The following practices can prevent Cross-Site Scripting:

- Encoding special characters

- Using XSS HTML Filter

- Validating user inputs

- Anti-XSS services/tools

3. Stored and Reflected XSS attacks Difference 

Stored XSS Attacks - These are attacks in which the injected scripts are persistently stored on the target servers. So when the victim requests information from the server, the malicious script is executed.


Reflected XSS Attacks - In this attack, the attacker tricks the user by any means to visit a link to a vulnerable website allowing the attacker to gain the user’s data.

4. HTTP Response Codes 

The HTTP response codes show whether or not a request has been completed and here is the meaning of the codes:


1xx (Informational) - The request has been received and is being processed.

2xx (Success) - The request was received and accepted successfully.

3xx (Redirection) - More action is required to finish it.

4xx (Client Error) - Request has the wrong syntax or cannot be completed.

5xx (Server Error) - The request was not performed by the server.

5. Man-In-The-Middle attack Prevention

MITM attack prevention is a common question in Network Security Interviews. You should know different  MITM attack techniques. 

a. Having stronger WPA/WEP Encryption on wireless access points avoids unauthorized users.

b. Use a VPN for a secure environment to protect sensitive information. It uses key-based encryption.

c. Public key pair-based authentication must be used in various layers of a stack for ensuring whether you are communicating the right things are not.

d. HTTPS must be employed for securely communicating over HTTP through the public-private key exchange.

6. System Security Hardening Techniques 

In general, system hardening describes a set of tools and procedures for managing vulnerabilities in an organization's systems, applications, firmware, and other components.


The goal of system hardening is to lower security risks by lowering possible assaults and compressing the attack surface of the system.


The many forms of system hardening are as follows: 

Hardening of 

a. Database

b. Application 

c. Server 

d. Operation system 

e. Network

7. Indicator of Compromise IOC Companies should monitor 

- DDOS activity 

- Privileged User Account Activity Anomalies 

- Log-In red flags 

- Unusual DNS Requests 

- HTML Response sizes as a sign of data breach. 

- Unhuman behavior of web traffic 

- Database read volume increasing 

- Ports mismatching for corresponding application 

- The unusual number of requests for specific files

8. Brute Force Attacks Prevention 

Brute Force Attack is a trial-and-error approach used by attackers to determine the correct credentials by repeatedly attempting all possible combinations.


The following procedures will help you avoid brute force attacks:

a. Increasing password complexity: To make passwords more secure, use a variety of character types.

b. Set a restriction on the number of failed login attempts.

c. Adding a second layer of protection to your account can help you prevent brute force assaults like two-factor authentication.

9. Data LeakageTypes and Definition 

Data Leakage is the illegitimate sending of data to an external destination or an unauthorized person within an enterprise. It has the ability to transport data both physically and electronically.


It often happens through the internet, emails, and mobile data storage devices.

Data Leakage Types: 

1) The Accidental Breach 

Most data breaches are unintentional. What happens when delivering confidential data, for example, an entity may select the incorrect recipient.

2) Malicious Intent in Electronic Communications 

The issue is that all electronic media are capable of file transmission and outside access sources across the internet.

3) Disgruntled Employee 

The authorized employee sends confidential data to an unauthorized entity.

10.  CSRF Attacks (Cross-site request forgery)

Cross-site Request Forgery (CSRF) occurs when an attacker deceives a victim into doing activities on their behalf.


The following methods can be used to avoid CSRF attacks:

a. Scripting such as java scripting should be disabled in your browser.

b. Do not visit other websites or open emails banking authentication or make any banking transactions on any other website, since this aids in the execution of dangerous scripts when authenticated to a financial site.

11. Hashing and Salting 

Hashing and salting are two terms that are relevant to each other. They have some major differences you should know as a Network Security Engineer. 


a. Hashing is a one-way function that converts data to a fixed-length value and is commonly used for authentication.

b. Salting is an additional level of security in the hashing process that adds extra value to passwords and alters the hash result.

12. What is Port Scanning Technique? 

- A port scan is a technique for identifying which ports are open on a network. Port scanning is similar to knocking on doors to determine whether somebody is home since ports on a computer are where information is transferred and received.

- A port scan on a network or server indicates which ports are open and listening (receiving data), as well as the presence of security measures like firewalls between the sender and the destination.

- It's also a popular reconnaissance starting point for attackers looking for a weak point of entry to hack into the network/device.

 The following are some of the most often used port scanning techniques:

a. UDP 

b. Ping Scanning 

c. Half-open TCP 

d. Stealth Scanning 

e. TCP connect 

13. Why is DNS monitoring Important? 

The Domain Name System (DNS) is a technology that converts human-readable domain names into computer-readable IP addresses. It allows websites to be hosted under a simple-to-remember domain name.


DNS monitoring is the process of checking DNS records to verify that traffic is appropriately routed to your websites, digital communications, services, and other endpoints.

14. What is the CIA Security Triad? 

The CIA triad contains three components, regardless of the source. A Network Security engineer should have a profound understanding of what these components mean.


a. Confidentiality refers to an organization's ability to keep its data confidential. This usually means that data should only be accessed or modified by authorized individuals and processes.


b. Integrity refers to the ability to trust data. It should be preserved in a proper state, protected from tampering, and accurate, authentic, and dependable.


c. Availability: Information should be available to authorized users whenever they need it, just as it is critical to keep unauthorized users out of an organization's data. This entails maintaining the availability of systems, networks, and devices.


All of these ideas are relevant to security experts of all types on their own. Information security experts may think about the link between these three notions, how they intersect, and how they contradict one another by grouping them into a triangle.


You should establish their infosec objectives and processes by examining the relationship between the three legs of the triad.

15. What is Risk Assessment? 

The risk assessment identifies and assesses the data assets that are vulnerable to cyber-attacks (such as customer data, hardware, and laptops) as well as the threats that may influence those assets.


It is primarily used to detect, assess, and prioritize risks inside businesses. The best method to analyze cybersecurity risks is to look for:


a. Relevant Company threats

b. Evaluate the effect of vulnerabilities if they are exploited.

c. external and internal vulnerabilities

16. What is Active Reconnaissance and how to prevent it?

Active reconnaissance is done by an intruder that engages with the target network to acquire information about vulnerabilities. 


Using a robust firewall and intrusion detection and prevention system is the simplest technique to prevent most port scan or reconnaissance attacks (IPS).

The firewall determines which ports are open to the public and who has access to them.


The IPS can identify ongoing port scans and bring them down before the adversary has a complete picture of your network.

17. A Comparison between IDS vs IPS?

IPS and IDS are two important terms in the Network Security field that you should be familiar with before the interview. 


Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) are two types of network security systems. IDS and IPS compare network packets to a cyber-threat database, which contains known cyber-attack signatures, and flags those that match.


The fundamental distinction is that an IDS is a monitoring system, whereas an IPS is a control system. IDS makes no changes to network packets, but IPS blocks packet delivery depending on the payload of the packet, similar to how a firewall blocks traffic based on IP address.


Intrusion Prevention Systems (IPS) are located between the outside world and the internal network, in the same region of the network as a firewall. If a packet represents a known security hazard, an IPS will proactively prohibit network traffic based on a security profile.


Intrusion Detection Systems (IDS) scan and filter traffic for signals that attackers are attempting to penetrate or steal data from your network using a recognized cyber threat. IDS systems detect a variety of activities such as security policy violations, malware, and port scanners by comparing current network activity to a known threat database.


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