Technical Support / IT Helpdesk Interview Prep
Entry point into tech. Helping users with technical issues. Path to many other roles.
General tips for this role
- CompTIA A+ is the gold standard entry cert. £400 total for both exams but huge ROI.
- Have a homelab story. Building your own setup (Plex server, Raspberry Pi, gaming PC build) signals genuine interest.
- Practise explaining technical things to non-technical people. Your grandmother is a great test audience.
- Mention you're studying for the next cert (Azure AZ-900, Google IT Support, Network+). Shows growth.
- Tech support is the entry point to MANY tech careers. 2 years of helpdesk + a cert = cloud engineer.
What is the OSI model and why does it matter?
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7 layers of networking: Physical, Data Link, Network, Transport, Session, Presentation, Application. Each layer has a specific job. When something doesn't work, knowing which layer is failing helps you debug. Most IT issues are at Layer 1 (cable unplugged), Layer 3 (IP/routing), or Layer 7 (application). Mnemonic: 'Please Do Not Throw Sausage Pizza Away'.
A user says 'the internet is down'. How do you troubleshoot?
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Start with the basics: (1) Is it ONLY them or everyone? Check status dashboards. (2) Can they reach OTHER websites? Just one site down ≠ internet down. (3) Is wifi connected? Try ethernet. (4) Reboot router. (5) Run ipconfig /all (or ifconfig on Mac) — got an IP? Got a default gateway? (6) Ping 8.8.8.8 — can you reach Google DNS? (7) nslookup — does DNS work? Most 'internet down' is wifi or DNS.
What's the difference between TCP and UDP?
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TCP: reliable, ordered, slower. Connection-based. Used for web (HTTP), email, file transfer. Guarantees delivery. UDP: fast, unreliable, no order guarantee. Used for video calls, gaming, DNS. Tolerates lost packets for speed. Rule of thumb: if losing data matters → TCP. If speed matters more than completeness → UDP.
How do you reset a Windows password if the user is locked out?
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If on a domain: use Active Directory Users and Computers (ADUC) or PowerShell (Set-ADAccountPassword). If local account: use the built-in admin account if available, or boot from a Windows install disk and use the password reset trick (replace utilman.exe). Modern setups use Microsoft Entra ID Self-Service Password Reset — train users to use it first.
A user's computer is slow. Walk me through your diagnostic.
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(1) Restart first — fixes 60% of issues. (2) Task Manager: CPU, RAM, disk usage. Find the resource hog. (3) Disk space — under 10% free? Clean up. (4) Startup programs — too many? Disable unnecessary. (5) Malware scan. (6) Check Windows Update — pending updates can lock resources. (7) Disk health (chkdsk, S.M.A.R.T.) — old HDD might be dying. (8) Last resort: reinstall Windows or replace hardware.
Explain DHCP in simple terms.
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DHCP = Dynamic Host Configuration Protocol. When a device joins a network, DHCP assigns it an IP address, subnet mask, default gateway, and DNS servers — automatically. Without DHCP, every device would need manual config. The DHCP server keeps a pool of available addresses and 'leases' one to each device. Common at home (your router is the DHCP server) and at work.
Describe a time you helped a frustrated user.
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STAR. Show: empathy first ('I hear how frustrating this is'), patience, clear explanation in non-technical language, follow-up to make sure it stayed fixed. The technical part of IT support is 30%. The other 70% is communication and patience.
End with what they said afterwards. 'They sent the team a thank-you email' is gold.
How do you stay calm when a user is yelling at you?
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Don't take it personally. Their anger is at the situation, not you. Acknowledge ('I understand this is frustrating'). Show you're focused on fixing it ('Let me get this sorted for you'). Avoid blame ('It sounds like the previous update caused this — let me check'). If they're abusive, you have the right to ask politely for respectful communication. Manager's job to back you up.
A user wants you to give them admin rights so they can install software themselves. What do you do?
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Politely no. Explain why: security policy, audit requirements, prevents accidental damage. Offer the alternative: 'I can install it for you now, or we can submit a request for the software to be added to our self-service portal'. Many companies use tools like Self Service Portals or Intune Company Portal so users can install approved software without admin rights.