Networks, Linux and Systems: The Technical Foundations of Cybersecurity Final quiz

Final quiz: Technical foundations of networks, Linux and systems

Pass mark: 75%. You can retry as many times as you need.

1 Which layer of the TCP/IP model is responsible for delivering data to the right program on a machine, using port numbers? Single answer Link layer Internet layer Transport layer Application layer

2 A laptop has the address 10.4.8.130/26. Which statements are correct? (several answers) Multiple answers possible Its subnet is 10.4.8.128/26. Its broadcast address is 10.4.8.255. Its broadcast address is 10.4.8.191. It is a private address.

3 A user complains that a website 'does not work'. Pinging its IP address succeeds, but opening it by name fails. What is the most likely area to investigate first? Single answer DNS name resolution The physical cable The default gateway The MAC address of the switch

4 Which statements about HTTPS and the browser padlock are correct? (several answers) Multiple answers possible It protects the content of requests and responses in transit. It proves that the site's owner is honest. It hides the destination address from the network. A phishing site can have a valid certificate for its own domain.

5 While capturing traffic with Wireshark, you want to avoid recording most of the traffic in the first place, keeping only DNS packets. Which feature do you use? Single answer A display filter such as dns Follow TCP Stream The Conversations statistics window A capture filter such as port 53

6 Why can a malicious machine on the same local network redirect traffic by abusing ARP, and what limits the attack? (several answers) Multiple answers possible ARP has no authentication and unsolicited replies are generally accepted. It works from anywhere on the Internet. It requires being in the same network segment. End-to-end encryption such as HTTPS keeps the content unreadable for the one in the middle.

7 A company wants guests' phones to be able to use the Internet but never reach the internal file server. What is the best design? Single answer Put guests in the employees' VLAN and ask them not to connect to the server. Hide the guest Wi-Fi name. Give guests a separate VLAN and subnet, with firewall rules allowing only Internet access. Disable the firewall for the guest network.

8 You build a lab with a deliberately vulnerable web application. Which network setup is the safest? Single answer Bridged adapter so that it gets an address from the home router. An internal network with static addresses, and NAT disconnected except for updates. Bridged adapter and the host firewall disabled. Any mode, since VMs are isolated by nature.

9 Which practices belong to a responsible personal lab? (several answers) Multiple answers possible Verify the checksum of images downloaded from the official website. Test the Wi-Fi network of a neighbour to practise. Take a snapshot before a risky experiment. Double-check that a target address belongs to the lab before running a tool.

10 A file shows the permissions -rw-r----- with owner alice and group dev. What does this mean? Single answer Everybody can read it, only alice can write. alice can read and write, members of dev can read, others have no access. alice and dev can both write, others can read. Only members of dev can read it.

11 On a Linux server, which actions are reasonable to reduce the attack surface? (several answers) Multiple answers possible Disable services that are not needed. Use chmod 777 on configuration files to avoid permission errors. Review listening ports with ss -tulpn and compare them with what you expect. Use sudo for specific tasks instead of working as root all the time.

12 In a bash script, you want to stop with an error if you accidentally use an undefined variable. Which line at the beginning helps? Single answer chmod +x script.sh #!/bin/sh -x echo $? set -u

13 In Active Directory, why should the administrator of the domain use a separate account from the one used to read email on a regular workstation? Single answer Because a single account cannot be used on two computers. To avoid exposing powerful credentials on machines that are exposed to email and web threats. Because separate accounts make the network faster. Because Windows limits each account to one login per day.

14 Which Windows events would you look at first to investigate repeated password guessing and a possible new persistence mechanism? (several answers) Multiple answers possible 4625 (failed logon) 4634 (logoff) 4740 (account locked out) 7045 (service installed)

15 Why is a plain SHA-256 hash a poor way to store passwords, and what should be used instead? Single answer It is fast, so guesses are cheap; use a slow dedicated function such as Argon2 or bcrypt with a unique salt. It is too slow; use MD5 instead. It cannot be computed for short passwords; use encryption with a shared key instead. It is reversible; use a longer hash name.

16 Which statements about symmetric and asymmetric cryptography are correct? (several answers) Multiple answers possible Symmetric encryption uses the same key to encrypt and decrypt. Asymmetric encryption is generally faster than symmetric encryption for large files. A signature made with a private key can be verified with the public key. TLS combines both: asymmetric to establish keys, symmetric to protect the data.

17 Your browser shows a certificate warning because the certificate does not cover the domain you are visiting. What does this mean and what should you do? Single answer The certificate is for another name; do not proceed with sensitive data, and find out whether it is a misconfiguration or an interception. The site is slow; click continue. The site is certainly safe because it has a certificate. Install the certificate authority offered by the site to remove the warning.

18 A developer needs a database password in an application. Which approach is the best? Single answer Write it in the source code and make the repository private. Embed it in the JavaScript sent to the browser. Share it in the team chat so that everyone has it. Load it at run time from a secrets manager or protected configuration, with a dedicated least-privilege account.

19 Which of the following are required to make a penetration test lawful? (several answers) Multiple answers possible Written authorisation from someone entitled to grant it. A clearly defined scope, including what is out of scope. Good intentions and a quick verbal approval. Rules of engagement and emergency contacts.

20 Which of the following best describes passive reconnaissance? Single answer Scanning all ports of the target at a slow speed. Trying default passwords on the target's login pages. Collecting information from public sources, without touching the target's systems. Interviewing the target's employees under a false identity.

21 During an authorised test, you reach a server that is not listed in the scope. What should you do? Single answer Test it quickly, because it is next to the target. Stop, do not explore, document it and inform the client contact. Copy its data for the report. Delete the log entries of your access.

22 Which measures help protect an SSH private key? (several answers) Multiple answers possible Protect it with a strong passphrase. Send it by email to colleagues who need access. Restrict file permissions so that only your account can read it. Use separate keys for separate purposes.