Reverse DNS Lookup
Find domain name from IP address
What is Reverse DNS?
Reverse DNS (rDNS) maps an IP address back to a domain name using PTR records. It helps verify server identity and is commonly used by email providers, security tools, and network administrators.
Our Reverse DNS Lookup tool checks PTR records instantly, so you can confirm if an IP address is properly mapped to a hostname.
Why Reverse DNS Matters
📧 Email Deliverability
Many email servers require rDNS to reduce spam and improve trust.
🛡️ Security Verification
Validate that an IP belongs to the expected domain or organization.
🧭 Network Troubleshooting
Identify misconfigured DNS and track services across IP ranges.
🔍 Reputation Checks
Confirm hostnames when auditing logs or reviewing traffic sources.
Common rDNS Issues
Missing PTR Record
Your IP has no reverse DNS entry, which can affect email delivery.
Hostname Mismatch
PTR record points to a hostname that doesn’t match your domain.
Stale DNS
Old PTR records remain after IP changes or migrations.
How to Fix Reverse DNS
✅ Contact Your Hosting Provider
PTR records are usually managed by the IP owner (hosting or ISP).
✅ Use Valid Hostnames
Ensure the PTR hostname resolves forward to the same IP (FCrDNS).
✅ Keep Records Updated
Update rDNS when migrating servers or changing providers.
✅ Re-test After Changes
DNS propagation can take time — check again after updates.
Frequently Asked Questions
What is reverse DNS (rDNS)?
Reverse DNS is the process of resolving an IP address back to its associated hostname. While standard DNS converts domain names to IP addresses (forward lookup), reverse DNS does the opposite — it maps IP addresses to domain names using PTR (Pointer) records.
Why is reverse DNS important for email?
Email servers perform rDNS lookups on incoming connections to verify the sender's identity. If your mail server's IP address doesn't have a valid PTR record, or if the PTR hostname doesn't match your sending domain, your emails are much more likely to be rejected or marked as spam.
What is FCrDNS (Forward-Confirmed reverse DNS)?
FCrDNS means the PTR record for an IP resolves to a hostname, and that hostname's A record resolves back to the same IP. This bidirectional verification is considered the gold standard for rDNS configuration and is required by many email providers.
Who manages PTR records?
PTR records are managed by the entity that controls the IP address block — typically your hosting provider or ISP. Unlike A records which you manage in your domain's DNS, PTR records must be configured by whoever owns the IP range.
How do I set up reverse DNS?
Contact your hosting provider or ISP and request a PTR record for your IP address pointing to your desired hostname. Most cloud providers (AWS, GCP, Azure) allow you to configure rDNS through their control panels.
Can one IP have multiple PTR records?
While technically possible, having multiple PTR records for a single IP is not recommended. RFC 1035 suggests a single PTR record per IP. Multiple PTR records can cause unpredictable behavior with email servers and other services that perform rDNS lookups.
Look Up Reverse DNS Instantly
Use CutUrls.com's free Reverse DNS Lookup tool to find the hostname for any IP address. No signup required.