How to check and verify PTR alignment?
Command line check:
- dig -x 192.0.2.1
- Returns PTR: mail.tidalmail.com
Forward verification:
- dig A mail.tidalmail.com
- Should return: 192.0.2.1
- Compare: If both match, FCrDNS passes.
Online tools:
- MXToolbox Reverse Lookup
- DNS Checker PTR Lookup
- These show PTR and check forward confirmation automatically.
- IPv6 check: dig -x with full IPv6 address. Same verification logic applies.
- Check after any IP or DNS changes.
Verify your ship's papers in both registries. Both should show consistent information.
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