Practical guide
How to run a bulk DNS lookup
Use this bulk lookup tool to check DNS, reverse PTR, or RDAP registration details across a whole list of domains or IPs at once and export the results. It turns a one-at-a-time chore into a single auditable run.
What this tool checks
The bulk tool takes a list of inputs — domains or IP addresses, one per line — and runs your chosen check against every entry. You pick the check (DNS records, reverse PTR, domain RDAP, or IP RDAP), and the tool returns one row per input in a single table, ready to export as CSV or JSON.
When to use it
Use bulk lookups for audits and migrations: verifying a record type across an entire portfolio of domains, mapping a block of IP addresses back to hostnames, or checking registration data on a list of domains or IPs at once. It is far faster than running the single-domain tools one entry at a time. For background on the record types you are auditing, see DNS records explained.
How to read the result
Each row pairs an input with the value the check returned, so you can review the whole list for outliers — a domain missing a record, an IP with no PTR, a host returning an unexpected status. Sort or filter the exported CSV to group failures together, then drill into any single entry with the matching single-domain tool for the full detail.
Common errors and what they mean
A row returns NXDOMAIN. That name does not exist — a typo or a decommissioned domain. A row returns SERVFAIL. The authoritative servers for that name are unreachable or its DNSSEC is failing. A row is blank or malformed. Check the input formatting — one entry per line, no stray characters. To tell the DNS failure modes apart, read NXDOMAIN vs SERVFAIL.
Exporting and reusing results
Every run exports to CSV for spreadsheets and audits, or JSON for feeding into another script. Because each row is self-contained, the export doubles as a snapshot you can diff against a later run to spot what changed across your domains over time.
Checks you can run in bulk
Each bulk run uses one check across the whole list. This is what each one returns and a typical audit it suits.
| Check | Input | Returns |
|---|---|---|
| DNS records | Domains | A / AAAA / MX / TXT / NS values per domain |
| Reverse PTR | IP addresses | The hostname each IP maps back to |
| Domain RDAP | Domains | Registrar, dates, status, nameservers |
| IP RDAP | IP addresses | Network block, holder, abuse contact |
Field notes
The real value of a bulk run is the diff. Export a CSV today, keep it, and run the same list again next month — comparing the two snapshots surfaces an expired domain, a changed MX, or a dropped PTR faster than any dashboard. Keep lists under the 200-input cap and split larger portfolios into batches so every run stays inside public-resolver rate limits.
Example: bulk A-record check across three domains
- Example input
example.com example.net example.org- Example result
example.com → 203.0.113.10 example.net → 198.51.100.25 example.org → NXDOMAIN
Two domains resolve to A records and one returns NXDOMAIN — the bulk run surfaces the missing record in a single pass instead of three separate lookups.
Related tools
Related guides
DNS Records Explained
Useful background when you are bulk-checking record types across many domains at once.
Read guideNXDOMAIN vs SERVFAIL
How to read the DNS failures that show up on individual rows of a bulk run.
Read guideRDAP vs WHOIS
What the RDAP registration data in a bulk lookup means and why it replaced WHOIS.
Read guideFAQ
What is a bulk DNS lookup?
How many domains can I check at once?
Can I export the bulk lookup results?
Which checks can I run in bulk?
Why did some rows in my bulk lookup fail?
Is the bulk lookup tool free?
Does the bulk tool store my list of domains?
Last reviewed: 2026-06-25.