rDNS (PTR) Lookup — What Is the Hostname of an IP Address?
Which hostname does an IP address resolve to? With our rDNS (reverse DNS) lookup tool, find out the PTR record of an IP in seconds. IPv4 and IPv6 are supported; we show the result together with forward verification (FCrDNS).
Example: 8.8.8.8 — type the IPv4 or IPv6 address you want to look up.
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KVKK CompliantWhat Is rDNS (Reverse DNS)?
rDNS (reverse DNS) works in exactly the opposite direction of regular DNS. While classic DNS translates a domain name into an IP address, reverse DNS translates an IP address into the hostname assigned to it. This resolution is done through the PTR record kept in the reverse zone the IP belongs to (in-addr.arpa for IPv4, ip6.arpa for IPv6).
In short, an rDNS lookup answers the question: "Who is this IP address, which server does it point to?" For example, a reverse DNS query for 8.8.8.8 returns the hostname dns.google. A reverse DNS lookup is the fastest way to identify the server behind an IP, diagnose network problems and, above all, check email reputation.
What Is a PTR Record and What Is It For?
A PTR record (Pointer Record) is the basic building block of reverse DNS. While an A record links a hostname to an IP, a PTR record does the opposite: it links an IP address to a hostname. This record is defined in the reverse DNS zone of the organization that manages the IP block (usually the hosting provider or ISP).
The most critical use of a PTR record is sending email. Receiving mail servers check whether the connecting IP has a valid rDNS / PTR record; mail coming from IPs that have no record or an inconsistent one is often treated as spam or rejected. That is why a PTR lookup is the first step in auditing mail deliverability.
Why Run an rDNS / PTR Lookup?
A reverse DNS lookup is not just a technical detail; it is used for many critical purposes, from email to security.
Email Deliverability
Having a correct PTR record on your mail server's IP is essential for your emails to arrive without landing in spam. You verify this with an rDNS lookup.
Reputation and Security
By seeing which hostname an IP points to, you detect suspicious connections and malicious servers and strengthen your network security.
Server Identity
With reverse DNS you quickly identify the server behind an IP address that appears in your logs and understand who it is.
Network Diagnostics
Seeing the hops in traceroute and similar tools as readable hostnames makes it easier to diagnose network problems.
FCrDNS Verification
By resolving the hostname in the PTR record back to an IP and checking that it matches (FCrDNS), you see whether the record is truly valid.
Setup Verification
When you allocate a new server or IP, you confirm by lookup that the rDNS / PTR record is defined correctly before going live.
What Information Does an rDNS Lookup Include?
When you run a reverse DNS lookup for an IP address, the tool gives you the following information.
IP Address and Type
The IP address queried and whether it is IPv4 or IPv6.
Hostname (PTR Record)
The hostname the IP address resolves to; if there are multiple PTR records, all are listed.
FCrDNS Status
Whether the PTR hostname resolves back to the same IP (the forward verification result).
Reverse Zone
The reverse zone name the query was made against (in in-addr.arpa or ip6.arpa form).
No-Record Status
If no PTR record is defined for the IP, a clear "PTR record not found" message is shown.
Instant and Free
Results come back in seconds; you can run reverse DNS lookups for as many IPs as you like.
The Difference Between Forward DNS and Reverse DNS
Forward DNS resolves a domain name to an IP address; it is what runs in the background when you type netvay.com into the browser, and it uses A/AAAA records. Reverse DNS does the opposite: it goes from an IP address to a hostname and uses the PTR record.
The two directions complement each other. For a domain-focused check you can use our WHOIS lookup tool; for IP-focused resolution you can use this rDNS / PTR lookup tool. If you want full control over your own server and a proper rDNS setup, our VDS server plans come with a dedicated IP.
rDNS / PTR and Email Deliverability
One of the most common problems in business email is sent messages landing in the recipient's spam folder. One of the main causes is that the sending mail server's IP address has no valid PTR record, or that the PTR hostname does not match the IP (an FCrDNS failure).
That is why one of the first things to do when setting up a new mail server is to define the IP's reverse DNS record correctly and confirm it with an rDNS lookup. For your business email needs you can review our hosting solutions, and for support with IP and rDNS settings you can contact us.
Frequently Asked Questions About rDNS and PTR
What is an rDNS (reverse DNS) lookup?
What is a PTR record used for?
What is the difference between an rDNS lookup and a WHOIS lookup?
Is the rDNS lookup free?
What does it mean when no PTR record is found for an IP?
What is FCrDNS (forward-confirmed reverse DNS)?
How do I change my server's rDNS / PTR record?
Can I run an rDNS lookup for IPv6 addresses?
Want Proper rDNS and PTR on Your Own Server?
NetVay VDS and server plans come with a dedicated IP; for mail deliverability we define the correct PTR record on your behalf. Set up your server, and we will take care of rDNS.
