Troubleshooting

15 articles
Interview Preparation Beginner

Linux Logs

Where Do Linux Logs Live? Two systems coexist on most modern distros: flowchart TB subgraph Sources KERNEL[Kernel Messages] …

Jan 20, 2026 Read more
Interview Preparation Intermediate

DNS Resolution Failures

Overview “Can’t resolve hostname” or intermittent DNS failures are common, and the resolution order Linux actually uses …

Jan 20, 2026 Read more
Interview Preparation Intermediate

High Load Average

Overview Load average is one of the most misunderstood Linux metrics. It’s not a CPU percentage — it’s roughly the average …

Jan 20, 2026 Read more
Interview Preparation Intermediate

Zombie & Defunct Processes

Overview A zombie (shown as Z or <defunct> in ps) is a process that has already finished executing but whose exit status hasn’t …

Jan 20, 2026 Read more
Interview Preparation Intermediate

Permission Denied Errors

Overview “Permission denied” is usually straightforward once you check the right thing — but there are several distinct causes …

Jan 20, 2026 Read more
Interview Preparation Advanced

Network Connectivity Issues

Overview “Can’t connect to X” can fail at any of several layers — the local network interface, routing, DNS, a firewall …

Jan 20, 2026 Read more
Interview Preparation Intermediate

Service Won't Start

Overview A systemctl start fails, or a service that should auto-start on boot never comes up. The fix depends entirely on WHY it failed, …

Jan 20, 2026 Read more
Interview Preparation Advanced

Slow Disk I/O

Overview Applications feel slow, but CPU and memory both look fine. The bottleneck is often the disk — either the physical/virtual storage …

Jan 20, 2026 Read more
Interview Preparation Advanced

High Memory Usage & OOM Kills

Overview A process was unexpectedly killed, or the server is grinding to a halt under memory pressure. Linux’s Out-Of-Memory (OOM) …

Jan 20, 2026 Read more
Interview Preparation Advanced

High CPU Usage

Overview CPU pegged at 100% (or a load average far above core count) usually has one of two shapes: a single runaway process, or many …

Jan 20, 2026 Read more