Reverse DNS & PTR Records

7 Min. Lesezeit Mittelstufe

While regular DNS translates domain names to IPs, reverse DNS does the opposite—translating IPs back to domain names. It's essential for email servers and security validation.

Was ist Reverse DNS?

Reverse DNS (rDNS) allows you to look up the hostname associated with an IP address. It uses special PTR (pointer) records stored in the in-addr.arpa domain.

For example, 192.0.2.1 is looked up as 1.2.0.192.in-addr.arpa.

Warum Reverse DNS wichtig ist

Reverse DNS serves several important purposes.

Email Deliverability

Mail servers reject messages from IPs without valid rDNS

Security Verification

Helps identify the source of network traffic

Logging & Analytics

Shows hostnames instead of IP addresses in logs

Spam Prevention

Forward-confirmed rDNS (FCrDNS) validates senders

Forward-Confirmed Reverse DNS

FCrDNS (Forward-Confirmed Reverse DNS) is when the reverse lookup matches the forward lookup. This is the gold standard for email authentication.

Example: 192.0.2.1 → mail.example.com (PTR) and mail.example.com → 192.0.2.1 (A record)

PTR: 192.0.2.1 → mail.example.com
A: mail.example.com → 192.0.2.1
✓ Forward-Confirmed Reverse DNS

Setting Up Reverse DNS

Reverse DNS is configured by whoever controls the IP addresses—typically the IP owner or leasing provider.

Wenn Sie IPs von IP Market leasen, konfigurieren wir Ihre PTR-Einträge entsprechend Ihren Anforderungen.

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