Free DNS tool
Reverse DNS Lookup
Turn any IP address back into its host name with a PTR lookup, the check mail servers run to weigh sender reputation.
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Lookups run in your browser over Google public DNS-over-HTTPS (Cloudflare as fallback). Nothing you enter is sent to Pulsetic.
DNS decides where your domain and email actually go. Pulsetic watches your domain and SSL certificate around the clock.
What is a reverse DNS lookup?
A normal DNS lookup turns a name into an address. A reverse DNS lookup goes the other way: it takes an IP address and finds the host name registered for it in a PTR record. The query runs against a special reverse zone (in-addr.arpa for IPv4, ip6.arpa for IPv6), where the address is reversed.
Reverse records are controlled by whoever owns the IP block, usually your hosting provider or ISP, not by the domain owner. That is why a server can have perfect forward DNS yet no PTR record at all.
Why reverse DNS matters for email
Receiving mail servers routinely run a reverse DNS lookup on a connecting IP and compare it with the forward record. A missing or mismatched PTR is a strong spam signal, so a sending server without valid reverse DNS often lands in junk folders or is rejected outright.
If you run your own mail server, ask your provider to set a PTR record that matches the host name your server announces in HELO, and confirm the forward A record points back to the same IP.
Look it up from the terminal
Prefer the command line? These return the same records this tool shows:
dig -x 8.8.8.8 +short
nslookup 8.8.8.8
Every DNS record type
What each record does. Each one has a dedicated lookup in the tabs above.
| Record | What it does | Example value |
|---|---|---|
| A | Maps a domain to an IPv4 address. | example.com → 93.184.216.34 |
| AAAA | Maps a domain to an IPv6 address. | example.com → 2606:2800:220:1:: |
| CNAME | Points one name at another name, as an alias. | www → example.com |
| MX | Names the mail servers that accept email for the domain, each with a priority. | 10 mail.example.com |
| TXT | Holds free-form text, used for SPF, DKIM, DMARC and domain verification. | v=spf1 include:_spf.google.com ~all |
| NS | Lists the authoritative name servers for the domain. | ns1.example.com |
| SOA | Start of authority: the primary name server and the zone refresh, retry and expiry timers. | ns1.example.com . 2026010101 |
| PTR | Reverse record: maps an IP address back to a host name. | 34.216.184.93.in-addr.arpa |
| SRV | Locates the host and port for a specific service. | _sip._tcp → 5060 sip.example.com |
| CAA | States which certificate authorities may issue SSL certificates for the domain. | 0 issue "letsencrypt.org" |
Frequently asked questions
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What is a PTR record?
A PTR (pointer) record maps an IP address back to a host name. It lives in the reverse DNS zone, in-addr.arpa for IPv4, and is the record a reverse DNS lookup returns.
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Why does my IP have no reverse DNS?
PTR records are set by the owner of the IP block, normally your hosting provider or ISP, not in your own domain zone. If there is no PTR, you usually have to request one from them.
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Does reverse DNS affect email deliverability?
Yes. Mail servers check that a sending IP has a PTR record and that it matches the forward DNS. A missing or mismatched PTR makes your mail look suspicious and can get it filtered or rejected.
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Can one IP have more than one PTR record?
It can technically, but it should not for mail. Multiple PTR records cause inconsistent reverse lookups, so a single PTR that matches your forward record is best practice.
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