Network Troubleshooting / IT Support Guides
Measure DNS, TCP and TLS stages with curl
A slow page can spend time resolving a name, establishing transport, negotiating TLS or waiting for the server. Timing a small request helps choose the next investigation.
Environment and inputs: Mixed platforms · each example identifies its shell or required tool
Try the diagnostic command
Use the stated shell and platform. Replace sample domains, addresses, services and paths with values from the system you are authorized to support.
curl --output /dev/null --silent --show-error --connect-timeout 5 --max-time 20 --write-out 'DNS=%{time_namelookup} TCP=%{time_connect} TLS=%{time_appconnect} FIRST=%{time_starttransfer} TOTAL=%{time_total}
' https://example.comHow to read the result
This Linux shell example prints cumulative elapsed times in seconds. Differences between milestones are more useful than treating every value as an independent duration.
What to do next
Repeat a few permitted requests and compare networks while recording proxy use. Investigate the stage that grows consistently and correlate it with server-side timing.
Before you make a change
This performs a GET and discards the body; use a harmless endpoint. Redirects, connection reuse and proxies affect interpretation, so this is not a full browser performance test.