Top Troubleshooting Interview Questions: Beginners to Advanced Level

The network Troubleshooting procedure typically involves several systematic steps to diagnose and resolve network problems. It starts with identifying the issue, including gathering user information and observing network behaviour. Next, we establish a theory of probable cause and then test this theory to determine the cause of the issue.   

Once the cause is identified, we implement a solution to resolve the problem, followed by verifying full system functionality and, if necessary, implementing preventive measures to avoid future issues. Documentation of the problem and its resolution is a crucial final step to aid in resolving future issues efficiently.

Netstat (network statistics) is a command-line tool showing network connections, routing tables, and several network interface and protocol statistics. It is also used for finding errors in the network and to understand the amount of traffic on the network as a type of performance measurement. 

A router is a device that connects several networks and routes network traffic across them. It operates at the OSI model's network layer, Layer 3, and can implement policy-based routing and network segmentation. A switch operates at the data link layer (Layer 2) and connects devices within a single network, forwarding data based on MAC addresses.   

It can create separate collision domains for each connected device. A hub operating at the data link layer simply broadcasts incoming network packets to all other ports, creating a single collision domain and significantly reducing network efficiency compared to a switch. 

Ping (Packet Internet Groper) is a diagnostic tool that tests the connectivity between two nodes or devices across a network. It sends Internet Control Message Protocol (ICMP) echo request packets to the target and waits for an echo reply. When measuring the time taken for the round trip and whether a reply is received, ping helps diagnose network connectivity issues and latency.  

A protocol analyser, also known as a network analyser or packet sniffer, is a tool used to capture and analyse the traffic over a network. It can decode the data packets and display the values of various fields in the packet, allowing the user to examine detailed aspects of the network traffic. This tool is invaluable for Troubleshooting network problems, analysing network performance, and detecting misuse or unauthorised activity.   

Safe mode is a diagnostic startup mode in Operating Systems (OS), especially Windows, used to troubleshoot and resolve issues. When a computer is started in safe mode, the OS loads a minimal set of drivers and services necessary for the system to run. This mode is used to diagnose and repair problems related to software, drivers, or settings that may cause the OS to behave erratically or not start usually. 

Basic Input/Output System (BIOS) is firmware that can perform hardware initialisation during the booting process (power-on startup) and provide runtime services for operating systems and programs. It is the first software run by a PC when powered on. It is responsible for preparing the computer so other software programs stored on various media can load, execute, and assume PC control. 

In networking, a domain refers to a collection of devices on a network that are managed as a unit with standard rules and procedures. On the Internet, a domain can be referred to as a part of the Domain Name System (DNS), which assigns human-friendly names to IP addresses. Domains are used to organise and control resources under a single authority, often reflecting an organisation's identity or brand. 

Cache memory is a small-sized dynamic computer memory that gives high-speed data access to a processor and stores frequently used computer programs, applications, and data. It also provides faster data storage and access by storing instances of programs and data routinely accessed by the processor. The primary aim of cache memory is to increase data retrieval speeds by reducing the time to access data from the main memory.      

Ghost imaging, also known as disk cloning, is the process of copying the contents of a computer's hard disk into a single compressed file or set of files, which are referred to as an image. The image can then be used to restore the original when needed or clone the system onto multiple computers, ensuring that all copies are identical regarding the operating system, installed software, and data.

A Software Development Kit (SDK) is a set of software development tools within one installable package, allowing developers to create applications for a specific platform. It typically includes one or more Application Programming Interfaces (APIs), programming tools, documentation, and often sample code. 

On the other hand, an API is a set of definitions and protocols that can be used for building and integrating application software. It allows several software applications to communicate with each other. The SDK is more comprehensive, including an API, but it also provides the tools to work with that API. 

Troubleshooting FTP server-related problems typically involves three steps:  

a) Verify connectivity: Use ping or similar network tools to ensure that the network connection between the client and the FTP server is intact. 

b) Check configuration: Review the FTP server and client configurations for any incorrect settings, including usernames, passwords, port numbers, and firewall settings that might block the connection. 

c) Review logs: Examine the FTP server and client logs for error messages or clues that can indicate what might be causing the problem, such as authentication failures or data transfer errors. 

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Answer: You can answer this question in this manner: “Yes, data recovery from a dead PC is often possible, depending on the condition of the hard drive or storage media. The process involves removing the hard drive from the dead PC and connecting it to a working computer as a secondary drive. Alternatively, one can use a USB to SATA/IDE adapter or docking station to connect the drive externally. If the drive is readable, data can be transferred directly. If the drive has issues, specialised data recovery software might be required to recover the data.” 

Answer: You can answer this question in this manner: “Yes, data recovery from a dead PC is often possible, depending on the condition of the hard drive or storage media. The process involves removing the hard drive from the dead PC and connecting it to a working computer as a secondary drive. Alternatively, one can use a USB to SATA/IDE adapter or docking station to connect the drive externally. If the drive is readable, data can be transferred directly. If the drive has issues, specialised data recovery software might be required to recover the data.” 

You can answer this question in this manner: “Yes, the 'no signal input' error can often be fixed by Troubleshooting the connection between the computer and the monitor. First, I will check if the monitor is powered on and properly connected to the computer. Then, I’ll verify that the video cable (HDMI, DVI, VGA) is securely connected to the monitor and computer. Then, I’ll try using a different cable or monitor to determine if the issue is with the hardware. Also, I will ensure the correct input source is selected on the monitor. If the problem persists, it might be due to the computer's graphics card or hardware issues, which will require further investigation.” 

Answer: You can answer this question in this manner: “A disk error refers to any issue that prevents a computer from accessing data on a hard drive, SSD, or other storage media. This can be due to hardware failure, corrupted files, bad sectors, or connection problems. If I received this message, I would restart the computer to see if the issue stays.   

Then, I would check all physical connections, run disk diagnostics using the computer's built-in utility or third-party software to assess the drive's health and attempt to repair disk errors. If data is inaccessible, I might use data recovery tools to retrieve important files.” 

Answer: You can answer this question in this manner: “Yes, testing my computer's RAM is important because faulty RAM can cause various issues, including crashes, blue screens, and data corruption. I will test RAM using built-in diagnostics tools like Windows Memory Diagnostic or third-party software like MemTest86. These tools run several tests on the RAM to check for errors or issues. Testing RAM is particularly advisable, especially if the system is unstable or when you install new memory modules.” 

Answer: You can answer this question in this manner: “Yes, I can solve DNS issues using a few steps: 

a) Restarting the router or modem to refresh the connection. 

b) Flushing the DNS cache on my computer to clear outdated or incorrect DNS information. This can be done by running the command ipconfig /flushdns in the command prompt (Windows) or clearing the DNS cache in macOS. 

c) Changing my DNS server settings to use a public DNS service like Google DNS or OpenDNS, which can be more reliable than your ISP's default servers. 

d) Checking for any incorrect DNS settings on my local network or computer.” 

Answer: You can answer this question in this manner: “I can Troubleshoot IP related problems in the following steps: 

a) Check the computer's IP configuration with commands like ipconfig (Windows) or ifconfig (Linux/macOS) to ensure the correct IP address, subnet mask, and default gateway. 

b) Renew the IP address using ipconfig /renew in Windows or restarting the network service in Linux/macOS. 

c) Verify that the DHCP server is functioning correctly if the computer is supposed to obtain an IP address automatically. 

d) Check for IP address conflicts on the network. 

e) Ensure the router and modem are functioning correctly, and there are no outages with your ISP.” 

Answer: You can answer this question in this manner: “Troubleshooting local connectivity issues involves:  

1. Checking physical connections such as cables and ports to ensure they are secure and undamaged. 

2. Verifying that network devices like routers and switches are powered on and functioning correctly. 

3. The ping command tests connectivity to local devices, including the default gateway. 

4. Ensuring the computer's network adapter is enabled and functioning correctly. 

5. Check for correct IP configuration and no IP conflicts on the network. 

6. Restarting network devices to resolve any temporary glitches. 

7. Updating network adapter drivers and firmware on network devices to the latest versions.” 

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