PTR Record Lookup

About PTR Record Lookup

PTR Record Lookup performs reverse DNS, finding the hostname an IP address claims as its name. It is the mirror image of an A record and it matters most for email: receiving mail servers routinely check that a sending IP has a PTR record, and that the hostname it returns resolves back to the same address. Mail from an IP with no reverse DNS, or with a generic hostname supplied by a hosting provider, is far more likely to be rejected or filtered regardless of how well SPF and DKIM are configured. The lookup uses a special naming scheme rather than the address itself: the IPv4 octets are reversed and placed under in-addr.arpa, so 8.8.4.4 is queried as 4.4.8.8.in-addr.arpa. IPv6 uses nibble-reversed notation under ip6.arpa. Because reverse zones are delegated to whoever controls the address block, you usually cannot set a PTR record at your DNS provider. It has to be set by your hosting company or ISP, which is the part that surprises people most often. Pair this with SPF Record Checker when diagnosing delivery problems.

DNS resolution happens in multiple stages. When you type a domain name, your browser first checks its own cache, then the OS resolver cache, then queries your configured DNS resolver (usually your ISP or a public resolver like 8.8.8.8 or 1.1.1.1). If none have the record cached, the resolver performs a recursive query: it asks the root name servers for the TLD servers (.com, .net, etc.), then asks the TLD servers for the authoritative name servers of the specific domain, and finally asks the authoritative servers for the actual record. This entire process typically completes in under 100ms. DNS-over-HTTPS (DoH) encrypts DNS queries in HTTPS traffic, preventing ISPs and network observers from seeing which domains you query. It was standardized in RFC 8484 in 2018 and is now supported by all major browsers. Google and Cloudflare both operate free public DoH endpoints (dns.google and cloudflare-dns.com). TXT records have become a critical security mechanism: SPF (Sender Policy Framework) records specify which servers are allowed to send email for a domain, DKIM (DomainKeys Identified Mail) records provide public keys for verifying email signatures, and DMARC records tell receiving mail servers what to do when SPF or DKIM checks fail. Checking these records is the first step in diagnosing email deliverability problems.

How to use PTR Record Lookup

  1. Enter a domain name (e.g. example.com, without http://).
  2. Select a record type (A, AAAA, MX, TXT, CNAME, NS, SOA, CAA, SRV, PTR) or an email policy check (DMARC, SPF, DKIM).
  3. Click Lookup to see live DNS records, then copy all results with one click.

Frequently Asked Questions

What is a PTR record?
A PTR record maps an IP address back to a hostname, which is the reverse of what an A record does. It is the basis of reverse DNS and is checked by mail servers to judge whether a sending host looks legitimate.
Why can I not add a PTR record at my DNS provider?
Because reverse DNS is delegated to whoever owns the IP address block, not the domain. You have to request it from your hosting provider or ISP. Adding a PTR record in your own zone has no effect.
Does a missing PTR record affect email delivery?
Yes, often significantly. Many receiving servers reject or heavily filter mail from IP addresses with no reverse DNS or with a generic provider hostname, even when SPF and DKIM pass. It is one of the first things to fix for a new mail server.
What is forward-confirmed reverse DNS?
It means the PTR record returns a hostname, and that hostname resolves forward to the same IP address. Mail servers check both directions, so a PTR pointing at a name that does not resolve back is treated as suspect.
Why is the query name reversed?
Reverse lookups use a dedicated zone. IPv4 addresses have their octets reversed and appended to in-addr.arpa, so 8.8.4.4 becomes 4.4.8.8.in-addr.arpa. This tool builds that name for you, so you can enter the address normally.

Related Tools

Also Available As