June 7, 2023


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Top 40 Network Admin and System Admin Interview Questions and Answers

Top 40 Network Admin and System Admin Interview Questions and Answers
Read Time:9 Minute, 37 Second

Welcome to Top 40 Network Admin and System Admin Interview Questions and Answers.

There is a lot of cross over in technology between computer networks and systems hence the need to combine the two career choices. In this article we will cover some of the most common questions that may come up during an interview.

Some answers are simplified to provide easier understanding and education.

1. Can you tell us about yourself?
This question is very important as your first opportunity to sell yourself as the best candidate for this job. You have to make sure that this answer is tailored to the position at hand; meaning only talk about yourself in the relevance to this position.

2.Explain the role of Windows Server.

Windows OS Server acts as a centralized computer that provides specific functions and predetermined rules for computers, users and components connected to a network.

3.What is Windows Domain?

Windows Domain provides access to user accounts, computers, printers and security features as part of database controlled by a domain controller.

4. What is a firewall?
Firewall is a filter between two or multiple computer sources; it blocks any incoming or outgoing traffic. Firewalls can be in software or hardware forms.

5. What is TCP/IP?
TCP is a Transmission Control Protocol that deals with establishing a connection between computers before any data is being sent; in other words it acts as the highway for data packets being sent back and forth used by various Protocols. For example; HTTP or FTP. TCP also controls and sorts out data packet receive order.

6. Can you explain the difference between HTTP and HTTPS?
HTTP stands for HyperText Transfer Protocol used by majority of websites as means of transmitting website data and it allows for use of hyperlinks. This Protocol mostly uses TCP port 80. HTTPS is a secure version of HTTP that allows for identity verification and low level encryption using TCP port 443.

7.What is DNS and which port does it use?

DNS stands for Domain Name System and it’s mostly used to interpret Domain names in to numeric IP address. For example; domain name CosmicNovo.com it’s IP address is DNS uses port 53 TCP or UDP.

8.How many queries does DNS perform and which ones?

DNS can perform two types of queries; Iterative and Recursive.

9.What is Active Directory?

A service of Windows Server OS, Active Directory is used for user and computer authentication within a Domain. It can also enforce security policies with use of GPOs which can also be used to push software installs across domain.

10.Active Directory database is located where?

Database is under the file name NTDS.DIT; and it is located in the %SystemRoot%\ntds folder of the server.

11.What is a Lingering Object?

If an Object is deleted from Active Directory while Domain controller is offline it can create a lingering object. When object is deleted from Active Directory a Tomb Stone (which is temporary) is created which then has to be replicated by Domain Controller before it expires.

12.What is RAID?

Stands for Redundant Array of Independent Disks and is used to provide data redundancy (mirroring) across multiple hard disks. It can also be utilized to improve read/write performance across the server by using striping configuration. For example RAID 1; two or more disks with identical data stored (redundancy). RAID 0; two or more disks, data distributed evenly to improve performance (no redundancy).

13.Which commands would you use in CMD to test network connectivity?

To test network connectivity ping, tracert or ipconfig commands can be used.

14.What does IntelliMirror do?

As part of Windows Server OS, IntelliMirror provides assistance in managing user data, computer information, applications and settings. This is configured with user Group Policy that defines business roles, group memberships and locations. For example, if a user moves to a different computer; the applications, settings, and stored files will follow.

15.How do you back up Active Directory?

Active Directory can be backed up by using NTBACKUP tool that comes with 2003 server. With 2008 server a command prompt is used to perform backup: type “wbadmin start systemstatebackup -backuptarget:e:” You can also perform a full server backup through Server Manager (OS 2012+).

16.Do you know what Garbage Collection is?

Garbage Collection is a process designed to free space inside Active Directory. This is performed by default every 12 hours (defrag).

17.Do you know what SYSVOL folder is?

System Volume folder is a directory that houses a copy of domain files found on a local hard drive within Domain Controller. This data is shared for purpose of replication across domain; for example user logon scripts and Windows Group Policy.

18.Explain what Group Policy is.

A Group Policy is used to control user’s desktops, computer configurations and permissions by creating a template for specific groups of members. This makes it easier to control and process large groups of users. For example; Tech Support may have different security permissions compared to regular computer users.

19.Can you name different types of email servers and ports used?

You can have two types of email servers:

Incoming Mail Server (POP3 port 110, IMAP 143, HTTP 80)

Outgoing Mail Server (SMTP port 25)

20.What is the difference between a forest and a domain?

A domain is a logic based group of computers, users and devices within Active Directory. A tree is a collection of domains; in case there are multiple trees formed a forest is created.

21.Do you know what Virtual Machine is?

Virtual Machine is an emulation version of Operating System. For example; you can have multiple copies of Windows running on a single computer.

22.Do you know what “Tattooing” the registry means?

The group policy will make the changes to user’s registry but once the group policy is no longer in effect, registry values would not revert back leaving them tattooed in.

23. What is a proxy or proxy server?
Proxy deals with filtering network traffic in a sense of preventing access to certain websites and can even monitor user web activity. It can block certain website from being accessed but it can also act as a measure of hiding the true origin at point of access.

24. Can you explain what UDP is?
UDP stands for User Datagram Protocol. Unlike TCP, UDP is constantly broadcasting a connection signal which can allow for faster connection speeds-with TCP you have to wait for connection confirmation which takes time. UDP sends out data without consideration of what is receiving it; sort of like Radio signal.

25. What is the loop-back IP address?
The loopback IP address is As part of troubleshooting network connections issues; it is used to test Network lnterface Card for functionality. If you ping this IP address and it completes successfully it means your hardware is okay.

26. What is DHCP?
DHCP stands for Dynamic Host Configuration Protocol. The main function of DHCP is to handle distribution of IP address on a network. Typically, IP address assigned by DHCP server are “Dynamic”, meaning that they are leased and released dynamically (except static). To explain it further, if you connect a PC to a network it will get a leased IP address and if you disconnected or move the PC it will be assigned a new IP address.

27. What is FTP and Port used?
FTP is a File Transfer Protocol used to transfer large files between computers with built in ability to pause transfer of data. Ports used by FTP are 20 and 21.

28. What is SSH and Port used?
Also known as Secure Shell; is used to establish a secure connection between devices which can be anything from computers to switches. For example; you can use SSH at a café and connect to any device anywhere; by establishing a configured Secure Shell tunnel between two devices. Thus, making the connection secure.

29. What is the maximum length of UTP cable allowed?
The maximum length of UTP is 90 to 100 meters for a single segment connection. If you have a switch or a repeater it can compensate for this limitation.

30. What are the layers of OSI model and how many?
There are 7 layers of OSI model: Physical Layer, Data Link, Network, Transport, Session, Presentation and Application.

31. What is the job of network layer?
Network Layer deals with routing, switching and transmitting of data from one point to another, but this layer is also responsible for error handling and packet sequencing.

32. Which types of network cables are used in networking?
Cat-5 runs at 100Mb/s maximum, Cat-5e can run up to 1Gb/s, and Cat-6 can run up to 1OGb/s. Speeds are rated at 100 meters maximum distance.

33. What is a Subnet Mask?
A Subnet Mask holds the information about network and hosts addresses under a subnet. In order for TCP/IP protocol to figure out this information it looks at the 32bit subnet mask number. Typical example is

34. Can you tell me the difference between a workgroup and a domain?
With a Workgroup you have a collection of systems that are connected to the same network but have their own set of rules and permission set at local level. With a Domain you have a group of systems that are bound by the rules of a Domain Controller.

35. Can you give an example of DNS issue.

If a host cannot be reached by it’s name over the network but can be reached using an ip address indicates a problem with DNS.

36. How would you analyze connection between a local host and a server?
A ”TRACERT” command is used to accomplish this test. Trace Route can provide detailed path information taken through switches, servers, computers in reaching final destination.

37. What is ipconfig command used for?
Ipconfig command is used to determine TCP/lP settings, DHCP configuration, DNS, Default Gateway, and Subnet Mask. It can also be used to change Local DHCP settings; for example ipconfig /release and /renew.

38. What is VPN?
A Virtual Private Network allows users to create a secure connection over public network such as internet. This is commonly used by mobile workers in order to access company’s network from a remote location.

39. What is a Network Switch?

A Network Switch is used to create or control a network at physical layer in which multiple devices are connected and share data. This is accomplished by receiving, processing and forwarding of data in form of data packets.

40. Why should we hire you?
Just as important as the very first question on this list; this is your last chance to tell this employer why you are the best choice for this position. You should talk about your experience and how you could use that to benefit the company.

Bonus Advice

As bonus advice; before going for an interview make sure you do research about the company you have interview with… A good place to start is taking a good look at the job description. If you need to study other aspects of IT please check out my channel for additional guides. Youtube.com/cobuman

I hope this guide gives you the confidence that you may need in order to get this awesome job.

Good luck to you all, and have a wonderful day.

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