Junior Penetration Tester Interview Questions UK: 8 Real Questions and What Interviewers Want

Applying for a Junior Penetration Tester job in the UK? Here is what you are likely to be asked. These questions come from our Junior Penetration Tester question bank of 16 questions, written for UK employers at junior level.

Eight Junior Penetration Tester interview questions, and what the interviewer is thinking

1. Walk me through how you would use Nmap to enumerate a target, and which scan options you would choose and why.

Why they ask: Nmap is the first tool every junior tester is expected to handle confidently.

2. How would you approach testing a web application using Burp Suite?

Why they ask: Web testing with Burp is a core entry-level competency.

3. What is the difference between a reverse shell and a bind shell, and when would you use each?

Why they ask: A common foundational technical question for entry-level testers.

4. What do you think a junior penetration tester does day to day, and what qualifications or certifications are you working towards?

Why they ask: They want realistic expectations and a development plan.

5. How do password attacks work, and how would you use Hashcat or John the Ripper responsibly in a test?

Why they ask: Credential attacks are standard in tests and need technical and ethical care.

6. What would you check when testing a Windows Active Directory environment as a junior tester, and what is Kerberoasting?

Why they ask: Internal tests are heavily AD-focused, and Kerberoasting is a staple technique.

7. You are testing a web application and discover you can read other users' personal data. What do you do?

Why they ask: They check professionalism and data handling when real data is exposed.

8. Tell me about a time you worked through a difficult technical challenge, such as a hack the box machine, CTF or lab, and how you approached it.

Why they ask: For a junior, practical projects demonstrate skills and mindset.

A sample answer to question 1

Walk me through how you would use Nmap to enumerate a target, and which scan options you would choose and why.

I would first confirm the target is in scope, then start with a fast TCP scan of all ports, such as nmap -p- -T4 with --min-rate where the client allows, to avoid missing services on non-standard ports. I'd follow with a targeted scan of the open ports using -sV for version detection, -sC for default scripts and -O for operating system fingerprinting, saving output in all formats with -oA so I can reference it in the report. I'd run a top UDP scan too, because services like SNMP and TFTP are often overlooked. For deeper checks I might use specific NSE scripts, such as smb-enum-shares or http-enum, with care around anything intrusive. I'd adjust timing on fragile or production systems to avoid causing disruption and mention that in my notes. Then I'd use the results to build a picture of the attack surface and decide what to examine manually, for example web servers, SMB, or database ports.

Common mistake to avoid: Running aggressive scans on fragile systems; Skipping UDP

Want the rest?

Full model answers, key points and common mistakes for all 16 questions are on the Junior Penetration Tester interview questions page. The first five are free, no sign-up needed.