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Interview Questions on Cyber Security


Cyber Security is one of the exceptionally pursued vocations in the IT business now. The interest develops as the need to get things online builds step by step. It additionally represents the business with the significant worry of tying down information resources for forestall any abuse of information. The increment in cybercrimes has become a danger for significant organizations, which propels them to employ Cyber Security experts to get organization resources for business achievement. Along these lines, you can exploit this market drift and be a Cyber Security master. Skim through these main 50 Cyber Security interview questions and replies to set yourself up for the meeting.


1. What is cryptography?


Cryptography aids to secure information from third parties who are called adversaries. It allows only the sender and the recipient to access the data securely.

2. What is traceroute? Mention its uses.


Traceroute is a network diagnostic tool. It helps track the route taken by a packet that is sent across the IP network. It shows the IP addresses of all the routers it pinged between the source and the destination.


  • It shows the time taken by the packet for each hop during the transmission.
  • When the packet is lost during the transmission, the traceroute will identify where the point of failure is.

3. What is a firewall? Mention its uses.


A firewall is a network security device/system, which blocks malicious traffic such as hackers, worms, malware, and viruses.


  • It monitors the incoming and outgoing network traffic. It permits or allows only data packets that agree to the set of security rules.
  • It acts as a barrier between the internal network and the incoming traffic from external sources like the Internet.
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4. What is a three-way handshake?

It is a process that happens in a TCP/IP network when you make a connection between a local host and the server. It is a three-step process to negotiate acknowledgment and synchronization of packets before communication starts.

Step 1: The client makes a connection with the server with SYN.

Step 2: The server responds to the client request with SYN+ACK.

Step 3: The client acknowledges the server’s response with ACK, and the actual data transmission begins.


5. What is a response code? List them.


HTTP response codes indicate a server’s response when a client makes a request to the server. It shows whether an HTTP request is completed or not.

1xx: Informational

The request is received, and the process is continuing. Some example codes are:

  • 100 (continue)
  • 101 (switching protocol)
  • 102 (processing)
  • 103 (early hints)

2xx: Success

The action is received, understood, and accepted successfully. A few example codes for this are:

  • 200 (OK)
  • 202 (accepted)
  • 205 (reset content)
  • 208 (already reported)

3xx: Redirection

To complete the request, further action is required to take place. Example codes:

  • 300 (multiple choice)
  • 302 (found)
  • 308 (permanent redirect)

4xx: Client Error 

The request has incorrect syntax, or it is not fulfilled. Here are the example codes for this:

  • 400 (bad request)
  • 403 (forbidden)
  • 404 (not found)

5xx: Server Error

The server fails to complete a valid request. Example codes for this are:

  • 500 (internal server error)
  • 502 (bad gateway)
  • 511 (network authentication required)


6. What is the CIA triad?


It is a security model to ensure IT security. CIA stands for confidentiality, integrity, and availability.

  • Confidentiality: To protect sensitive information from unauthorized access.
  • Integrity: To protect data from deletion or modification by an unintended person.
  • Availability: To confirm the availability of the data whenever needed.


7. What are the common cyberattacks?


Here is a list of common cyberattacks aimed at inflicting damage to a system.

  1. Man in the Middle: The attacker puts himself in the communication between the sender and the receiver. This is done to eavesdrop and impersonate to steal data. 
  2. Phishing: Here, the attacker will act as a trusted entity to perform malicious activities such as getting usernames, passwords, and credit card numbers.
  3. Rogue Software: It is a fraudulent attack where the attacker fakes a virus on the target device and offers an anti-virus tool to remove the malware. This is done to install malicious software into the system.
  4. Malware: Malware is a software that is designed to attack the target system. The software can be a virus, worm, ransomware, spyware, and so on.
  5. Drive-by Downloads: The hacker takes advantage of the lack of updates on the OS, app, or browser, which automatically downloads malicious code to the system.
  6. DDoS: This is done to overwhelm the target network with massive traffic, making it impossible for the website or the service to be operable.
  7. Malvertising: Malvertising refers to the injections of maleficent code to legitimate advertising networks, which redirect users to unintended websites.
  8. Password Attacks: As the name suggests, here, the cyber hacker cracks credentials like passwords.


8. What is data leakage?


Data leakage means the unauthorized transmission of data from an organization to an external recipient. The mode of transmission can be electronic, physical, web, email, mobile data, and storage devices, such as USB keys, laptops, and optical media.

Types of data leakage:

  • Accidental leakage: The authorized entity sends data to an unauthorized entity accidentally.
  • Malicious insiders: The authorized entity intentionally sends data to an unauthorized entity.
  • Electronic communication: Hackers make use of hacking tools to intrude the system.

9. Explain port scanning.

A port scan helps you determine the ports that are open, listening, or closed on a network. Administrators use this to test network security and the system’s firewall strength. For hackers, it is a popular reconnaissance tool to identify the weak point to break into a system.

Some of the common basic port scanning techniques are:

  1. UDP
  2. Ping scan
  3. TCP connect
  4. TCP half-open
  5. Stealth scanning

10. Explain brute force attack and the ways to prevent it.

A brute force attack is a hack where the attacker tries to guess the target password by trial and error. It is mostly implemented with the help of automated software used to login with credentials.

Here are some ways to prevent a brute force attack:

  1. Set a lengthy password
  2. Set a high-complexity password
  3. Set a limit for login failures

11. Explain the difference between hashing and encryption.

Hashing Encryption
A one-way function where you cannot decrypt the original message Encrypted data can be decrypted to the original text with a proper key
Used to verify data Used to transmit data securely
Used to send files, passwords, etc. and to search Used to transfer sensitive business information

12. What is the difference between vulnerability assessment (VA) and penetration testing (PT)?

Vulnerability Assessment (VA) Penetration Testing (PT)
Identifies the vulnerabilities in a network Identifies vulnerabilities to exploit them to penetrate the system
Tells how susceptible the network is Tells whether the detected vulnerability is genuine
Conducted at regular intervals when there is a change in the system or network Conducted annually when there are significant changes introduced into the system

13. Mention the steps to set up a firewall.

Following are the steps you have to follow to set up a firewall:

  1. Username/password: Alter the default password of a firewall device.
  2. Remote Administration: Always disable the Remote Administration feature.
  3. Port Forward: For the web server, FTP, and other applications to work properly, configure appropriate ports.
  4. DHCP Server: Disable the DHCP server when you install a firewall to avoid conflicts.
  5. Logging: Enable logs to view the firewall troubleshoots and to view logs.
  6. Policies: Configure strong security policies with the firewall.

14. What is SSL encryption?

Secure Socket Layer is a security protocol that is used for the purpose of encryption. It ensures privacy, data integrity, and authentication in the network like online transactions.

The following are the steps for setting up an SSL encryption:

  1. A browser connects to an SSL-secured web server.
  2. The browser requests the server’s public key in exchange for its own private key.
  3. If it is trustworthy, the browser requests to establish an encrypted connection with the web server.
  4. The web server sends the acknowledgment to start an SSL encrypted connection.
  5. SSL communication starts to take place between the browser and the web server.

15. What steps will you take to secure a server?

A server that is secured uses the Secure Socket Layer (SSL) protocol to encrypt and decrypt data to protect it from unauthorized access.

Below are the four steps to secure a server:

Step 1: Secure the root and administrator users with a password

Step 2: Create new users who will manage the system

Step 3: Do not give remote access to administrator/default root accounts

Step 4: Configure firewall rules for remote access


16. What is the difference between HIDS and NIDS?


Host Intrusion Detection System Network Intrusion Detection System
Detects the attacks that involve hosts Detects attacks that involve networks
Analyzes what a particular host/application is doing Examines the network traffic of all devices
Discovers hackers only after the machine is breached Discovers hackers at the time they generate unauthorized attacks


17. Mention the difference between symmetric and asymmetric encryption.


Differentiator  Symmetric Encryption Asymmetric Encryption
Encryption Key Only one key to encrypt and decrypt a message Two different keys (public and private keys) to encrypt and decrypt the message
Speed of Execution Encryption is faster and simple Encryption is slower and complicated
Algorithms RC4, AES, DES, and 3DES RSA, Diffie-Hellman, and ECC
Usage  For the transmission of large chunks of data For smaller transmission to establish a secure connection prior to the actual data transfer


18. What is the difference between IDS and IPS?


Intrusion Detection System Intrusion Prevention System
A network infrastructure to detect intrusion by hackers A network infrastructure to prevent intrusions by hackers
Flags invasion as threads Denies the malicious traffic from threads
Detects port scanners, malware, and other violations Does not deliver malicious packets if the traffic is from known threats in databases


19. What are the different layers of the OSI model?


It is a model introduced by the International Organization for Standardization for different computer systems to communicate with each other using standard protocols.

Below are the various layers of the OSI model:

  • Physical layer: This layer allows the transmission of raw data bits over a physical medium.
  • Data link layer: This layer determines the format of the data in the network.
  • Network layer: It tells which path the data will take.
  • Transport layer: This layer allows the transmission of data using TCP/UDP protocols.
  • Session layer: It controls sessions and ports to maintain the connections in the network.
  • Presentation layer: Data encryptions happen in this layer, and it ensures if the data is in usable/presentable format.
  • Application layer: This is where the user interacts with the application.


20. What is a VPN?


VPN stands for virtual private network. It is a private network that gives you online anonymity and privacy from a public Internet connection. VPN helps you protect your online activities, such as sending an email, paying bills, or shopping online.

How does a VPN work?

  1. When you make a VPN connection, your device routes the Internet connection to the VPN’s private server, instead of your Internet Service Provider (ISP).
  2. During this transmission, your data is encrypted and sent through another point on the Internet.
  3. When it reaches the server, the data is decrypted.
  4. The response from the server reaches the VPN where it is encrypted, and it will be decrypted by another point in the VPN.
  5. At last, the data, which is decrypted, reaches you.


21. What do you understand by risk, vulnerability, and threat in a network?


  • Threat: A threat can cause potential harm to an organization’s assets by exploiting a vulnerability. It can be intentional or accidental.
  • Vulnerability: A vulnerability is a weakness or a gap in the security system that can be taken advantage of by a malicious hacker.
  • Risk: A risk happens when the threat exploits a vulnerability. It results in loss, destruction, or damage to the asset.


22. How do you prevent identity theft?


To prevent identity theft, you can take the following measures:

  1. Protect your personal records.
  2. Avoid online sharing of confidential information.
  3. Protect your Social Security Number.
  4. Use strong passwords, and change them at regular intervals.
  5. Do not provide your bank information on untrustworthy websites.
  6. Protect your system with advanced firewall and spyware tools.
  7. Keep your browsers, system, and software updated.

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23. Who are White Hat, Grey Hat, and Black Hat Hackers?


Black Hat Hackers
A Black Hat Hacker uses his/her hacking skills to breach confidential data without permission. With the obtained data, the individual performs malicious activities such as injecting malware, viruses, and worms.

White Hat Hackers
A White Hat Hacker uses his/her hacking skills to break into a system but with the permission of the respective organizations. They are professionals known as Ethical Hackers. They hack the system to identify its vulnerability and to fix it before a hacker takes advantage of it.

Grey Hat Hackers
A Grey Hat Hacker has the characteristics of both a Black Hat Hacker and a White Hat Hacker. Here, the system is violated with no bad intention, but they do not have the essential permission to surf the system, so it might become a potential threat at any time.


24. When should you do patch management, and how often?


Patch management has to be done immediately once the updates to the software is released. All the network devices in the organization should get patch management in less than a month.


25. What are the ways to reset a password-protected BIOS configuration?


BIOS being hardware, setting it up with a password locks the operating system. There are three ways to reset the BIOS password:

  1.  you need to unplug the PC and remove the CMOS battery in the cabinet for 15–30 minutes. Then, you can put it back.
  2. You can use third-party software such as CmosPwd and Kiosk.
  3. You can run the below commands from the MS-DOS prompt with the help of the debug tool. For this method to work, you need to have access to the OS installed.
o 70 2E
o 71 FF

This will reset all BIOS configurations, and you need to re-enter the settings for it.


26. Explain the MITM attack. How to prevent it?


In the Man-in-the-Middle attack, the hacker eavesdrops on the communication between two parties. The individual then impersonates another person and makes the data transmission look normal for the other parties. The intent is to alter the data, steal personal information, or get login credentials for sabotaging communication.

These are a few ways to prevent an MITM attack:

  1. Public key pair based authentication
  2. Virtual private network
  3. Strong router login credentials
  4. Implement well built Intrusion Detection System(IDS) like firewalls.
  5. Strong WEP/WPA encryption on access points


27. Explain the DDoS attack. How to prevent it?


Distributed denial-of-service attack overwhelms the target website, system, or network with huge traffic, more than the server’s capacity. The aim is to make the server/website inaccessible to its intended users. DDoS happens in the below two ways:

Flooding attacks: This is the most commonly occurring type of DDoS attack. Flooding attacks stop the system when the server is accumulated with massive amounts of traffic that it cannot handle. The attacker sends packets continuously with the help of automated software.

Crash attacks: This is the least common DDoS attack where the attacker exploits a bug in the targeted system to cause a system crash. It prevents legitimate users from accessing email, websites, banking accounts, and gaming sites.

To prevent a DDoS attack, you have to:

  1. Configure firewalls and routers
  2. Recognize the spike in traffic
  3. Consider front-end hardware
  4. Empower the server with scalability and load balancing
  5. Use anti-DDoS software


28. Explain the XSS attack. How to prevent it?


Cross-site scripting also known as XSS attack allows the attacker to pretend as a victim user to carry out the actions that the user can perform, in turn, stealing any of the user’s data. If the attacker can masquerade as a privileged victim user, one can gain full control over all the application’s data and functionality. Here, the attacker injects malicious client-side code into web services to steal information, run destructive code, take control of a user’s session, and perform a phishing scam.

Here are the ways to prevent an XSS attack:

  1. Cross-check user’s input
  2. Sanitize HTML
  3. Employ anti-XSS tools
  4. Use encoding
  5. Check for regular updates of the software


29. What is an ARP, and how does it work?


Address Resolution Protocol is a communication protocol of the network layer in the OSI model. Its function is to find the MAC address for the given IP address of the system. It converts the IPv4 address, which is 32-bit, into a 48-bit MAC address.

How ARP works:

  1. It sends an ARP request that broadcasts frames to the entire network.
  2. All nodes on the network receive the ARP request.
  3. The nodes check whether the request matches with the ARP table to find the target’s MAC address.
  4. If it does not match, then the nodes silently discard the packet.
  5. If it matches, the target will send an ARP response back to the original sender via unicast.


30. What is port blocking within LAN?


It refers to restricting users from accessing a set of services within the local area network. The main aim is to stop the source from providing access to destination nodes via ports. Since all applications run on the ports, it is necessary to block the ports to restrict unauthorized access, which might violate the security vulnerability in the network infrastructure.

Advanced Cyber Security Interview Questions and Answers


31. What are the protocols that fall under the TCP/IP Internet layer?


Application Layer NFS, NIS, SNMP, telnet, ftp, rlogin, rsh, rcp, RIP, RDISC, DNS, LDAP, and others
Transport Layer TCP, SCTP, UDP, etc.
Internet IPv4, ARP, ICMP, IPv6, etc.
Data Link Layer IEEE 802.2, PPP, etc.
Physical Layer Ethernet (IEEE 802.3), FDDI, Token Ring, RS-232, and others


32. What is a botnet?


A botnet, which is also known as a robot network, is a malware that infects networks of computers and gets them under the control of a single attacker who is called a ‘bot herder.’ A bot is an individual machine that is under the control of bot herders. The attacker acts as a central party who can command every bot to perform simultaneous and coordinated criminal actions.

The botnet is a large-scale attack since a bot herder can control millions of bots at a time. All the botnets can receive updates from the attacker to change their behavior in no time.


33. What are salted hashes?


When two users have the same password, it will result in the creation of the same password hashes. In such a case, an attacker can easily crack the password by performing a dictionary or brute-force attack. To avoid this, a salted hash is implemented.

A salted hash is used to randomize hashes by prepending or appending a random string (salt) to the password before hashing. This results in the creation of two completely different hashes, which can be employed to protect the users’ passwords in the database against the attacker.