Why these tools matter
When a site does not open, guessing wastes time. Basic network tools help narrow the failure from “the service is broken” into a smaller question: DNS, routing, firewall, port binding, HTTP response, or application behavior.
Tool checklist
ping checks basic reachability, but it is not proof that a web service is healthy. Many systems block ICMP.
traceroute shows the route packets take across networks. It is useful when traffic dies before reaching the server.
curl tests the actual HTTP layer:
curl -I https://example.com
This can confirm status code, redirects, TLS behavior, and whether Nginx is responding.
dig checks DNS:
dig example.com
This answers whether the domain resolves to the expected address.
ss checks listening ports on the server:
ss -lntp
This shows whether a process is actually listening on ports such as 80, 443, or an internal app port.
Debugging order
The useful order is:
- Does DNS point to the right place?
- Does the server accept traffic on the expected port?
- Does Nginx respond?
- Does Nginx reach the backend?
- Does the app return the expected response?
This gives every incident a path instead of a panic.
