dns troubleshooting

Found 3 articles tagged with "dns troubleshooting"

How to Flush DNS on Mac, Windows, Linux

Run ipconfig /flushdns on Windows, dscacheutil and killall -HUP mDNSResponder on macOS, resolvectl flush-caches on Linux, and learn which cache you can't clear.

DevToolLab Team·November 6, 2026

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How to Read DMARC Reports (Aggregate XML)

Tutorial

7 min

How to Read DMARC Reports (Aggregate XML)

A DMARC aggregate report is a daily XML tally per sending IP. Read policy_evaluated, not auth_results, to see why SPF can pass while DMARC still fails.

DevToolLab Team·October 30, 2026

Tutorial

8 min

How to Check SSL Certificate Expiration

Pipe openssl s_client into openssl x509 -enddate to see when a server's SSL certificate expires. Plus -checkend for cron, curl, Python, Node and PFX files.

DevToolLab Team·October 5, 2026