Bulk reverse DNS lookup: PTR records for up to 500 IP addresses
In short: Paste IPv4 or IPv6 addresses and get each one's PTR hostname, whether that hostname resolves back to the same IP, and whether the name looks auto-generated. Limit: It reads public DNS only. A PTR record says what the IP's owner published, not who uses the IP now.
A bulk reverse DNS lookup finds the PTR record of many IP addresses at once. Paste up to 100 IPv4 or IPv6 addresses, or 500 after a free Google sign-in, and each row shows its PTR hostname, whether that hostname resolves back to the same IP (forward-confirmed reverse DNS), and whether the name looks auto-generated. Download the results as CSV.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. Check your list free nowSee pricing
Sample result
8.8.8.8 points to dns.google, which resolves back to 8.8.8.8: forward-confirmed.
- IP
- 8.8.8.8
- PTR
- dns.google
- Resolves back
- Yes
What this means for you
A sending IP needs a PTR whose hostname resolves back to it, or mail providers count it against you.
- PTR record for every IPv4 and IPv6
- Forward-confirm check on each hostname
- Generic pool names flagged
- CSV of hostnames and addresses
- PTR
- Reverse DNS
- FCrDNS
By SimpleVerifier Team · Last updated
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Checking the servers behind a list you're about to send to?
- Reverse DNS tells you how an IP is set up, not whether an address works. To see which addresses on a list can receive mail, upload it at /verify.
- The first 100 email checks are free with a Google sign-in, no card. Each row comes back valid, invalid or risky, with the reason.
- For your own sending IPs, check the IP blacklist check next, since a listing hurts more than a missing PTR.
How do I do a reverse DNS lookup on many IPs at once?
- Paste IP addresses, one per line, up to 100 a run, or 500 after a free Google sign-in. Lines from a log or a Received header work too: the first IP on each line is used.
- Press Look up PTR records. Each IP gets one PTR query, then an A or AAAA query for each hostname it names (up to five), 25 IPs a request.
- Read each row: the PTR hostname, Confirmed when it resolves back to the same IP, and Generic when it looks like an auto-generated pool name.
- Filter to IPs with no PTR or no forward match, and download the CSV with every hostname and the addresses it resolves to.
Example
- You enter
- Three IPs:
8.8.8.8,1.1.1.1and192.168.1.10. - You get
- 8.8.8.8:
dns.google, Confirmed (it resolves back to 8.8.8.8). 1.1.1.1:one.one.one.one, Confirmed. 192.168.1.10: Not checked, a private address with no public PTR. Download the CSV. - Limits
- Up to 100 a run without an account and 500 when signed in with Google, counted over a minute. 25 IPs a request; DNS only.
How does a reverse DNS lookup work?
An IP address is turned into a name under a special zone and looked up as a PTR record: 203.0.113.7 becomes 7.113.0.203.in-addr.arpa, as RFC 1035 defines, and an IPv6 address becomes 32 reversed hex digits under ip6.arpa (RFC 3596). The answer is the hostname the IP's owner chose.
This tool runs that query for every IP you paste, then looks up each hostname forward. When the hostname resolves back to the same IP, the row says Confirmed: that is forward-confirmed reverse DNS, the form mail servers check. It sends nothing to the IPs themselves.
Why does reverse DNS matter for email?
Mailbox providers read it when your server connects. Google's email sender guidelines say sending IPs must have a PTR record, and that its hostname must resolve back to the sending IP. Mail from an IP without one is more likely to be rejected or filtered as spam.
A name like 203-0-113-7.dynamic.example.net also counts against you: it looks like a home or pool connection rather than a mail server. The Generic label marks those names. It's a pattern match on the IP's digits and words like dynamic, dsl or pool, so treat it as a hint, not a verdict.
Who sets the PTR record?
Whoever controls the IP block, usually your hosting provider or ISP, not the owner of the domain. You can't add a PTR in your domain's DNS zone. To change one, open your server provider's control panel (most VPS hosts have a reverse DNS field) or ask their support.
If you send through Google Workspace, Microsoft 365 or an email platform, their IPs already have PTR records, and you can't change them. Reverse DNS is your job only on servers and IPs you run yourself.
What can I use a bulk PTR lookup for?
Auditing a pool of sending IPs before a warm-up, checking that every IP in a new range has a matching hostname, and reading the IPs from bounce messages or Received headers to see which servers they belong to.
To find which network owns each IP, use the bulk IP to ASN lookup. For one IP with a fuller explanation, use the single reverse DNS lookup.
How is this different from running dig -x for each IP?
| This tool | dig -x or nslookup | |
|---|---|---|
| IPs per run | 100, or 500 signed in | One per command |
| Forward-confirm check | Done for every hostname | A second command per hostname |
| Generic name flag | Shown per row | You judge it |
| CSV export | Yes | Copy and paste |
Who uses this tool, and for what?
- Email server admins
- Check every IP in a sending pool has a PTR whose hostname resolves back to it before warming them up.
- Deliverability consultants
- Paste the IPs from a client's bounce logs or headers and see which servers have missing or generic reverse DNS.
- Hosting providers
- Audit a new IP range for missing or mismatched PTR records after delegation.
- Security teams
- Turn a list of IPs from a log into hostnames to see whose servers they are.
What can’t this tool tell you?
- It reads public DNS only. A PTR record says what the IP's owner published, not who uses the IP now.
- Generic is a pattern match on the hostname, so it can miss pool names or flag a real server name that contains its IP.
- Only the first five hostnames of an IP are forward-checked.
- Private, loopback and reserved addresses are skipped.
- Up to 100 IPs a run without an account, 500 signed in.
Common questions
- How do I find the hostname of many IP addresses?
- Paste them into a bulk reverse DNS lookup like this one. It queries each IP's PTR record and shows the hostname, whether it resolves back to the same IP, and a CSV of the results.
- Is this bulk reverse DNS lookup free?
- Yes. Up to 100 IPs a run without an account, and up to 500 a run when you sign in with Google, with no card.
- What does Confirmed mean?
- That the PTR hostname resolves back to the same IP address. This is forward-confirmed reverse DNS, the check Gmail and other providers run on sending servers.
- Why does an IP have no PTR record?
- Its owner never set one. Many cloud and home IPs have none or a generic one. Only the provider that controls the IP can add it.
- Can I look up private IP addresses?
- No. Private, loopback and reserved ranges such as 10.0.0.0/8 and 192.168.0.0/16 have no public PTR records, so they are skipped and marked as not checked.
- Does it support IPv6?
- Yes. IPv6 addresses are looked up under ip6.arpa and forward-checked with AAAA records.
Sources
A tidy list can still be full of dead addresses.
Extracting, deduplicating and syntax checks all work on the text of an address. None of them can tell whether the mailbox exists. Only the server that hosts it can answer that, through an SMTP check, and that is what the paid product does.
- Upload the cleaned file as it is: CSVs up to 100,000 rows
- A real SMTP mailbox check on every row, with catch-all detection
- Small list? Starter at $9/mo covers 2,500 emails a month, cancel anytime
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.