Running your own BIND server gives you full control. Managed DNS gives you anycast, DDoS protection, and an API. Here is how to choose and how to switch.

Running your own authoritative DNS server gives you full control. Here is how to set up BIND9 for rootlog.in, create zone files, and test the setup.

Almost every 'DNS propagation delay' is actually a TTL issue. Here is how caching really works, plus /etc/hosts tricks and nsswitch.conf.

Most network problems are DNS problems. Here is a repeatable methodology for finding the root cause of any DNS issue.

A DNS zone is a database of records. Knowing how to read and query them with dig, host, and nslookup is a core sysadmin skill.

Every DNS query starts with a resolver. Understanding recursive vs iterative resolution is essential for troubleshooting and performance tuning.

DNS is the phonebook of the internet. Every lookup starts at the root servers and walks down the hierarchy — this is exactly how it works.

tcpdump is the standard packet analyzer on Linux. Every senior admin uses it to capture raw network traffic and diagnose connectivity issues at the packet level.

Everything on Linux is a file. lsof lists open files and the processes that own them. ss replaces netstat with faster, more detailed socket introspection.

strace intercepts and records system calls made by a process. It is the single most valuable tool for understanding what a program is actually doing at the kernel level.

Bash scripting is a must-have skill for Linux administrators. It lets you automate repetitive tasks and streamline system management.

Linux file permissions are the foundation of system security. Learn how to use chmod, chown, and umask to control access to files and directories.