System administrator interview questions

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1. discuss the steps you would take to secure a [MySQL/PostgreSQL/MS SQL] installation, including best practices for setting up user accounts, implementing encryption, and configuring firewalls?
2. how do you prevent lateral movement of a hacker who successfully attacked one of your database applications?

1. How does firewalld work on CentOS systems and which file format do the rulesets have?
2. What is UFW on Debian?
3. What is the difference between nftables and iptables?
4. What is the role of systemd network namespaces?

1. Can you explain how DKIM works in email security and how it can be used to prevent email spoofing and fraud?
   1. What are the steps for setting up DKIM for a domain and how does it interact with other email security technologies?

1. How does the ACME DNS challenge work in the process of obtaining SSL/TLS certificates from a certificate authority?
   1. What are the benefits and limitations of using this challenge method?

1. What is the purpose of using GPG subkeys and how can they be used to enhance the security of GPG encryption?

1. How does the IPSec protocol ensure secure and encrypted communication between two or more endpoints, and what are the differences between transport mode and tunnel mode?
2. What are differences and use cases for OpenVPN and IPSec VPN?
   1. what are the benefits and challenges of each solution in terms of scalability, security, and compatibility?