Bulk DNS Lookup
Bulk DNS lookup for up to 50 domains or IP addresses in one run: resolve A, AAAA, MX, TXT, NS, PTR or ASN for every target and export the whole table as CSV.
About Bulk DNS Lookup
Bulk DNS Lookup takes a list of up to 50 domains or IP addresses, resolves one record type for every entry in a single run, and returns a row per target with either the values found or the reason there were none. It replaces the shell loop around dig that most engineers write when they need to reconcile an inventory, check where a set of domains currently points, or confirm reverse DNS across a block of addresses. Results download as CSV, so the output goes straight into a spreadsheet or a ticket.
Reading one name at a time hides the exception; a table of fifty makes it obvious. PTR queries follow the normal reverse path through in-addr.arpa for IPv4 and ip6.arpa for IPv6 (RFC 1035 and RFC 3596), which is where the classic failure shows up: a mail server with no PTR, or one whose PTR does not match its forward record, is deferred or rejected by receivers that require forward-confirmed reverse DNS, as RFC 1912 recommends. The same sweep exposes names that answer for A but not AAAA, and MX sets still pointing at a former provider.
Queries run server-side from our own European infrastructure in a bounded, concurrency-limited batch, so a paste of fifty names does not become an unbounded burst from your own machine. Duplicate entries are collapsed before anything is sent, the input accepts newlines, commas, semicolons or spaces as separators, and a target that fails is reported on its own row as no record rather than aborting the batch. MX rows show preference and exchange together, TXT strings arrive concatenated, and the ASN option maps IPs or prefixes using public RIPE NCC data.
How to use it
- 1Choose the record type: A, AAAA, MX, TXT or NS for names, PTR for reverse lookups from IP addresses, or ASN to map IPs and prefixes to the network announcing them.
- 2Paste your targets into the box, one per line, up to 50; commas, semicolons and spaces also work as separators.
- 3Select the Look up button, which shows how many entries it counted, so you can confirm the list parsed as you expected.
- 4Scan the Result column for rows reading no record or carrying an error, since those are the exceptions worth investigating.
- 5Select Download CSV to save the full table for a spreadsheet, a ticket, or a diff against your inventory.
Common use cases
- -Auditing where a portfolio of domains currently points before a hosting or CDN migration.
- -Reconciling a CMDB or asset spreadsheet against what DNS actually publishes today.
- -Confirming reverse DNS is set on every address in a mail-sending range before the first send.
- -Checking which domains in a list still have MX records at a previous mail provider.
- -Mapping a list of client IP addresses to their announcing ASN while investigating traffic or abuse.
Frequently asked questions
- How many domains can I look up at once?
- Up to 50 per run. Duplicate entries are removed before any query is sent, so a list with repeats goes further than it looks, and if you paste more than 50 the tool says so and processes the first 50. For a larger inventory, split the list into batches of 50; the CSV export from each run can then be concatenated into one file.
- Can I do a bulk reverse DNS (PTR) lookup?
- Yes. Select PTR and paste IP addresses rather than hostnames. Each address is queried through in-addr.arpa for IPv4 or ip6.arpa for IPv6, and the resulting hostnames are listed. Addresses with no PTR come back as no record, which is exactly what you want to find before sending mail from a range, since many receivers treat a missing or mismatched PTR as a spam signal.
- What does the ASN option in a bulk lookup return?
- For each IP address or prefix it returns the autonomous system numbers currently seen announcing the covering prefix, with the holder name where one is published. It answers the question of which network a list of addresses belongs to, in one pass, using public RIPE NCC data. That is useful for abuse triage, peering research, or working out whether a set of addresses sits behind a single provider.
- Can I export bulk DNS results to CSV?
- Yes. Every run offers a Download CSV button that writes one row per target with the values found, or the error text where the lookup failed. The file is generated in your browser from the results already on screen, so nothing extra is sent anywhere, and the simple target and result layout imports cleanly into a spreadsheet or a diff against an existing inventory.