Top 50 Cyber Security Interview Questions and Answers

Cyber Security Interview Questions - Networking

We will start with a set of cyber security interview questions based on networking.

01. What is the OSI model? Explain the different layers of the OSI model.

The Open Systems Interconnection (OSI) model is a reference model that describes how applications interact with each other over a computer network. It has seven layers; they are as shown below:

1. Physical Layer: This is the lowest level of the OSI model. Here, data is converted into an electrical impulse and sent through a physical medium. It is also responsible for the physical connection between the devices.
2. Data Link Layer: Here, the data packet is encoded and decoded into bits. This layer looks into the node to node delivery of a message.
3. Network Layer: In this layer, datagrams are transferred from one to another. The functions here are routing and logical addressing.
4. Transport Layer: This layer is responsible for end-to-end connections. The data in this layer is called segments. This is where TCP and UDP protocols work.
5. Session Layer: This layer controls signals between computers. The session layer establishes, maintains, and ends connections between processes.
6. Presentation Layer: It is responsible for translating data into the application layer format. Here, the data is formatted, encrypted, and then sent to the next layer.
7. Application Layer: Finally, here, services are provided to the end-users. The application layer deals with any sort of data that the application of a machine generates, like a user input such as a password, and so on.  

02. Define Unicasting, Multicasting, and Broadcasting.

Unicast, Multicast, and Broadcast are the three methods by which we transmit data over a network. 

1. Unicast: It sends the information from a single user to a single receiver. We use this for point-to-point communications. 
2. Multicast: Here, data is sent from one or more sources to multiple destinations. 
3. Broadcast: Broadcast is known as one-to-all, i.e., the communication is between a single user and several receivers.  

03. What is DNS?

DNS stands for Domain Name System. It maps the domain name into its corresponding IP address. 

As seen below, the DNS server provides the website's IP address. 

04. What is a Firewall?

It is software or hardware that blocks incoming or outgoing traffic from the internet to your computer. They are responsible for securing a network. 

The figure above shows how good traffic is allowed to enter the user's network. Similarly, the figure below shows how the firewall blocks the bad traffic, thereby protecting the user's network.

A few common types of firewalls are:

1. Packet-filtering Firewalls: These are the most common type of firewalls that analyze packets and let them pass through only if they match an established security rule-set.
2. Proxy Firewalls: They filter network traffic at the application level.
3. Stateful Multilayer Inspection (SMLI) Firewalls: These filter packets at the network, transport, and application layers. Here, the packets are compared to the known trusted packets.

05. What is a VPN?

VPN is also called a Virtual Private Network; it connects a VPN server and a VPN client. It creates a safe encrypted tunnel across the internet. 

As seen below, the user has a VPN client installed on the machine. The VPN client then creates an encrypted tunnel to the VPN server; thus, information is received and sent to the internet securely. 

06. What are the advantages of distributed processing?

Distributed processing describes various computer systems that use more than one processor to run an application. Multiple computers across different locations share the same processor. The advantages of distributed processing are:

1. Data Recovery: When one computer loses data, another interconnected computer can recover this loss of data.
2. Reliability: Any glitch in one machine does not affect the processing since it will use several other machines.
3. Lower Cost: Several cost-effective minicomputers are used instead of using costlier mainframe machines.
4. Easy to expand: Depending on the data processing amount, we can attach additional computers to the network.

07. What is TCP/ IP?

Transmission Control Protocol (TCP) is a set of communication protocols used to interconnect network devices on the internet. It defines how data should be transmitted over the internet by providing end-to-end communication.

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Internet Protocol (IP) is all about routing every individual packet to ensure it reaches its destination. The TCP/IP model is a compressed version of the OSI model. It consists of four layers; they are:

08. What do you mean by ipconfig and ifconfig?

09. What is the difference between Domain and Workgroup?

10. What is Data encapsulation in networking?

Data encapsulation is the process of adding headers and trailers to data. The data link layer binds each packet into a frame that consists of the hardware address of the source and the destination computer.

Let's now head to the next section of this article on cybersecurity interview questions.

Cyber Security Interview Questions - Software and Programming

This section will take you through a set of cyber security interview questions based on software and programming.

11. How do you keep your computer secure?

There are a few steps that one has to implement in order to keep their computer secure. A few of these steps are:

1. Implement a 2-way or multi-factor authentication 
2. Use uncommon alphanumeric passwords and secure them 
3. Update your computer regularly
4. Install a good antivirus to protect your computer from malware
5. Have a specialized firewall to keep attacks at a minimum
6. Have anti-phishing software installed to identify fraudulent mails
7. Use encryption to reduce data leakage and loss
8. Finally, it is very crucial to secure your DNS 

12. Discuss security-related aspects between C, C++, and Java.

13. What are the different sources of malware?

Malware is a malicious software that harms the security of your device. The different sources of malware are:

1. Pop-ups
2. Removable media
3. Documents and executable files
4. Internet downloads
5. Network connections
6. Email attachments
7. Malicious advertisements

14. How does email work?

As you can see below, here, there are two servers, both using SMTP. We have John and Jack, and in this scenario, John wants to send an email to Jack. Thus, they have an email client installed on their machine connected to the mail exchange server, which has a DNS server that maps the routing and maps the exchange server and inboxes. 

So when John composes the message and clicks on send, he should be connected to a mail exchange server where the email is sent through that particular person's inbox. So John's inbox will then be validated, and that email will then be sent through the DNS server through the internet and will be received by the recipient mail server. 

While John composes the mail, the from the field will have his email address, and the to the field will have Jack's email address. When he clicks on send, it will go to their exchange server. The exchange server will then validate the inbox and identify where the inbox is located for Jack, and then through the internet, it will be sent to the mail server of Jack. 

The mail server will then identify the right inbox that email needs to be sent to, and it stores the email in that particular inbox of the recipient. This way, when Jack accesses his inbox, the email from John will be waiting in his inbox. Jack can then reply the same way John sent the email.

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15. What are the types of threats a company can face?

There are several threats that a company can face; on a broader scale, we can classify them as:

1. Natural Threats: These include natural disasters beyond human control, threats like a tornado, fire, floods, etc.
2. Man-made: These are threats where humans are the cause, like theft, hacking, etc.
3. Technical: These threats could be either a software bug or a server fail, or any technical failure.
4. Supply System: Any electric outage or short circuit kind of problem falls under this category. 

16. What are black box and white box testing?

In black box testing, the tester has zero knowledge of the IT infrastructure. Here, the testers will be unaware of the application, and they would have to gather information all by themselves. Based on the gathered information, testers will identify system vulnerabilities, if any. It is important as it emulates the attack of an external hacker.

A white box attack emulates an insider who can be an employee in the organization trying to make unvalidated profits. In this form of testing, the tester has complete knowledge of the IT infrastructure. 

17. What is use-case testing?

Use-case testing is a functional black box testing. Testers use it to get the test scenarios to exercise the entire system from start to finish. For example, when the software is made for users to use for documentation. The testers will test all the cases that a user can do like shown below:

18. What is static and dynamic testing?

19. What are the test levels in software testing?

The test levels in software testing are:

1. Module testing: It checks subprograms, procedures, routines, and subroutines in a program.
2. Integration testing: Here, the combined parts of an application of software are tested to check if they function correctly or not.
3. System testing: System testing tests the entire system or software or any application.
4. Acceptance testing: The quality assurance team does this testing to check if the clients' requirements are met or not.

20. What are the valuable steps to resolve issues while testing?

The following steps can be implemented to resolve issues while testing:

1. Record: Log and resolve the problems which have happened
2. Report: Report issues to the higher-level managers
3. Control: Define the issue management process

Let's now proceed to the next section of this article on cybersecurity interview questions.

Cyber Security Interview Questions - Operating Systems and Applications

This section of cyber security interview questions is based on operating systems and applications.

21. What is virtual memory?

Virtual memory is a storage allocation method in which a secondary memory (hard disk) is used as the primary memory (RAM).

22. What are the different scheduling algorithms?

Listed below are the different scheduling algorithms:

1. First come, first serve: The process which requests the CPU first gets the CPU allocation first.
2. Shortest job first: Here, the process with the shortest execution time should be selected for execution next.
3. Priority scheduling: Here, the scheduler selects the tasks to work as per the priority.
4. Multiple level queues: Processes are assigned to a queue based on a specific property like the process priority, size of the memory, etc.
5. Shortest remaining time: Here, the process will be allocated to the task, which is closest to its completion. 
6. Round Robin: Each process that comes, in turn, gets an equal share of time.

23. What are the steps involved in hacking a server or network?

This is more of an ethical hacking question; the steps involved in hacking a server or network are:

1. Reconnaissance: In this phase, all the evidence and information on the target are gathered.
2. Scanning: Here, you take the gathered information and apply various tools and techniques to collect more in-depth information on the targets.
3. Gain access:  In this phase, accurate attacks are leveled against the targets enumerated in the second phase.
4. Maintain access: Here, hackers ensure that they have a way back into the compromised system.
5. Cover tracks: Finally, attackers try to conceal their success and avoid detection by security professionals.

24. What are the various sniffing tools?

 Given below is a list of a few of the sniffing tools:

1. Wireshark: It is used to analyze the network in detail
2. TCPDUMP: It analyzes the packets which are transmitted
3. MSN Sniffer 2: MSN Sniffer 2 is the first chat sniffing tool
4. Ettercap: This tool is perfect for the man in the middle attack
5. Dsniff: It is a password and network analyzing tool
6. EtherApe: It displays the network activity graphically

25. What is an operating system?

It is a software program that provides a computer hardware platform to communicate and operate with the computer software.

For input and output functions, the operating system acts as an intermediate between the program and computer hardware. Some examples of OS are Windows, Unix, Android, Linux, etc.

26. What is the difference between microkernel and macrokernel?

27. What are the various types of operating systems?

The various types of operating systems are:

1. Batched OS: The computer operator places the jobs coming from input devices into batches.
2. Distributed OS: Many computers are interconnected with communication networks.
3. Time-sharing OS: Time-sharing OS minimizes the response time.
4. Multi programmed OS: The operating system uses CPU scheduling to separate jobs.
5. Real-time OS: Here, the OS gives maximum time to critical operations.

28. What is the difference between logical address space and physical address space?

29. Which shells are used in Linux?

The shells used in Linux are:

1. bash: Bourne again shell is the default for Linux distributions
2. ksh: Korn shell is a high-level programming shell that supports associative arrays and built-in operations
3. csh: C shell does spelling corrections and job control
4. zsh: Z shell provides unique features like filename generation, startup files, etc.
5. fish: Friendly interactive shell which provides features like auto-suggestions, configurations, etc.

30. What are the process states in Linux?

The process states in Linux are:

1. Ready: In this state, the process is created and is ready to run.
2. Running: Here, the process is being executed.
3. Blocked or wait: In this state, the process is waiting for input from the user.
4. Completed or Terminated: Here, either the process completed execution or was terminated by the OS.
5. Zombie: In this state, the process is terminated, but the process table still holds the information.

Let's go to the next section of this article on cybersecurity interview questions.

Cyber Security Interview Questions - Cyberattacks

This section of cyber security interview questions is based on cyberattacks. 

31. What is SQL injection?

An SQL injection vulnerability enables an attacker to inject malicious input into an SQL statement. This attack allows the attackers to view, edit, and delete tables in a database. Additionally, attackers can also obtain administrative rights.

The types of SQL injection are:

1. In-band SQLi: Error-based and Union-based
2. Blind SQLi: Boolean-based and Time-based
3. Out-of-bound SQLi

32. What is Spoofing?

In spoofing, an attacker pretends to be another person or organization and sends you an email that appears to be legitimate. The email looks almost genuine, and it is hard to spot such a fake one. An example of such an email is as follows:

33. What is a Distributed Denial of Service attack (DDoS)?

A Denial of Service attacks' objective is to flood networks and systems with traffic to exhaust their resources and bandwidth. By doing so, a website is unable to cater to legitimate service requests. When hackers use multiple systems to launch this attack, it is known as a Distributed Denial of Service (DDOS) attack.

34. How to avoid ARP poisoning?

The following steps can avoid ARP poisoning:

1. Using Packet Filtering: Packet filters filter out and block packets that have the same source address data.
2. Keeping away from trust relationships: Organizations develop protocols that do not depend on trust relationships.
3. Utilize ARP Spoofing Software: ARP spoofing software gauges the information before transmission and blocks the information that is spoofed.

35. What is ransomware?

Ransomware blocks victims from accessing personal files and demands a ransom to regain access. It is a type of malware. There are three categories of ransomware:

1. Scareware: It is a form of malware that uses social engineering to cause fear or anxiety to manipulate users into buying unwanted software.
2. Screen Lockers: Here, the users' computers are locked, and it displays an official-looking message. It thus prevents them from logging in to their computers.
3. Encrypting Ransomware: The ransomware displays a message demanding payment in return for the private asymmetric key needed to decrypt the encrypted file's symmetric keys.

36. What is the difference between active and passive cyberattacks?

As seen below, in an active attack, the attacker attempts to disrupt a network's normalcy, edits data, and alters the system resources.

Whereas, in a passive attack, the hacker intercepts the data traveling through the network. Here as seen below, the intruder eavesdrops but does not modify the message. 

37. What is a social engineering attack?

Social engineering attacks manipulate people so that they end up sharing their confidential information. This attack has three categories:

1. Phishing Attack: Here, the user opens the mail with the attachment and unknowingly downloads the virus.
2. Spear Phishing Attack: Here, the attacker targets a specific individual or a group of people.
3. Whaling Phishing Attack: Whaling Phishing attack is a type of attack that specifically targets wealthy, powerful, and prominent individuals.

38. What is the man in the middle attack?

Here, the attacking computer takes the IP address of the client. The server continues communicating with the attacker, unaware of this.

39. Who are black hat hackers and white hat hackers?

Black hat hackers are highly skilled individuals who illegally hack into a system. The motive behind this is mostly for monetary gain. These individuals are also known as security crackers. 

White Hat Hackers, also called ethical hackers, are individuals who discover vulnerabilities in a computer network. Such a hacker works to defend organizations and governments.

40. What are honeypots?

Honeypots are computer systems that are used to lure attackers. It is used to deceive attackers and defend the real network from any attack. As seen below, the real network is safeguarded.

Let's now head to the final section of this article on cybersecurity interview questions.

Cyber Security Interview Questions - Cryptography

This section of cyber security interview questions is based on the concept of cryptography.

41. Define cryptography, encryption, and decryption.

Ethical hackers use cryptography to secure information. It involves converting data from a readable format to a non-readable format and vice versa.  

Encryption: Converting a message from a readable state to a scrambled state, making no sense. In the below example, Key = Alphabet + 2.

Decryption: The message is decrypted using a secret key that is known only to the recipient. Decryption  = Alphabet - 2 in the given example.

42. What is the difference between ciphertext and cleartext?

Ciphertext refers to the text which is encrypted and undecipherable. The message received after decryption is known as cleartext. This text is understandable.

43. What is a block cipher?

This refers to the method of encrypting the plain message block by block. The plain message is broken down into fixed-size blocks and then encrypted.

44. What is Public Key Infrastructure?

Public Key Infrastructure (PKI) is a set of policies that secures the communication between a server and a client. It uses two cryptographic keys, public and private. 

PKI enables trusted digital identities for people. PKI grants secure access to digital resources. The core of PKI is a certificate authority, which ensures the trustworthiness of the digital data.

45. What is RSA?

RSA is a public-key cryptosystem that is used for secure data transmission. RSA stands for Rivest, Shamir, and Adleman, who are the inventors of the technique. It is an asymmetric cryptography algorithm that works on both public and private keys. Here, the encryption key is public, and the decryption key is kept private. 

46. What are a few of the alternatives to RSA?

The alternatives to RSA are as follows:

1. Duo Security
2. Okta
3. Google Authenticator
4. LastPass

47. What are the prime objectives of modern cryptography?

The prime objectives of modern cryptography are:

1. Confidentiality: Confidentiality helps in keeping the information safe from unauthorized people. 
2. Non-repudiation: Non-repudiation prevents denial in an electronic transaction.
3. Authenticity: Authenticity helps in identifying the source of the created information.
4. Integrity: Integrity makes sure that the data received by the receiver is not modified.

48. What is SAFER?

Secure and Fast Encryption Routine(SAFER) is a block cipher. This has a 64-bit block size and a byte-oriented algorithm. SAFER's encryption and decryption procedures are highly secure. This technology is used widely in applications like digital payment cards.

49. How does the Public Key Infrastructure (PKI) work?

The working of Public Key Infrastructure (PKI) at a macro level is as follows:

1. Firstly, the request for the Digital Certificate is sent to the appropriate CA (Certificate Authority).
2. Once the request is processed, the Digital Certificate is issued to the person requesting it.
3. After that, the Digital Certificate gets signed by confirming the identity of the person.
4. Now, the Digital Certificate can be used to encrypt the cleartext into a ciphertext, which is sent from the sending party to the other party.

50. What is the Blowfish algorithm?

It is a 64-bit symmetric encryption algorithm. The same secret key is used for encrypting and decrypting. Here, the operations are based on exclusive ors and additions on 32bit words. The key has a maximum length of 448 bits; it is variable. It is also used to generate several subkey arrays.

So, those were the top 50 cyber security interview questions that can help you crack your cybersecurity interview. 

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Conclusion

Now that you know the various cyber security interview questions that can be asked in an interview, you can prepare by referring to the given answers for each of these concept-based cybersecurity questions. 

Here, we had a look at a plethora of cyber security interview questions based on concepts like networking, software and programming, operating system and applications, cyberattacks, and cryptography. I hope this article on cyber security interview questions was useful. 

Do you have any questions for us related to this article? If so, then please put it in the comments section of the article. Our experts will answer your queries right away!