Start with the question you need to answer: is the host reporting, which resource is under pressure, does a service accept connections, or has scheduled work been missed? These are different observations, so choose a check that matches the problem rather than treating one successful result as proof that everything is healthy. Use the guides below to understand each feature and its scope.
Read CPU and memory graphs alongside load, filesystem utilization, network receive rate and disk read rate to put a resource problem in context. Explore Linux server metrics for the server-wide view and history, rather than assuming a single busy graph identifies the cause.
A server reporting through its agent answers a different question from an externally reachable address or open service port. Understand server uptime and keep host availability separate from the health of the applications and scheduled tasks that depend on it.
ICMP reachability and a TCP connection describe different parts of a service's availability; an open port alone does not establish application health. Read about ping and port checks to choose the observation that fits a host, database, mail service or custom daemon.
A backup or report can be missed while the machine itself remains available, so a healthy host is not evidence that scheduled work completed. Explore cron job monitoring for the scheduled-task topic and the common reasons jobs fail silently.
Use a threshold with a duration to distinguish sustained problems from brief spikes, with warning and critical levels where appropriate. Explore server alerts for rule examples, recovery messages and the alerting topic without repeating those details in every metric guide.
Choose from email, Slack, Telegram and webhook rather than making people watch graphs continuously. See notification channels for the channel overview and consider who needs to receive a message before deciding where a rule should send it.
Choose your platform for VPS, dedicated machines, Linux hosts running cPanel, and Docker hosts.
For HTTP(S) availability and certificate topics, start with website checks.
New to the topic? Start with what is server monitoring.
