DNS tools for DevOps: bulk lookup, FCrDNS, and fleet auditing
Bulk DNS lookup: audit entire domain fleets
Post-migration verification, pre-launch DNS audits, decommission checks — DevOps work routinely involves checking the same record type across dozens or hundreds of domains. DNS Buddy's bulk lookup accepts up to 256 domains at once. Paste your list, pick your record type (A, AAAA, MX, TXT, NS, CNAME, SOA, PTR, CAA), and get results for every domain in a single pass. Export to CSV for tickets, runbooks, or incident evidence.
Try Bulk DNS LookupFCrDNS validation at scale
Forward-confirmed reverse DNS (FCrDNS) checks that a host's PTR record matches its A record — the IP resolves to the hostname, and the hostname resolves back to the same IP. Mail servers check this. Security scanners flag it. Some rate-limiting policies enforce it. DNS Buddy's bulk FCrDNS tool validates this relationship across your server inventory in one request, making it fast to surface mismatches before they cause incidents.
Try Bulk FCrDNSReverse DNS for IP fleet auditing
When provisioning new infrastructure or auditing existing servers, you need to verify that PTR records are correctly set for your IP ranges. Reverse DNS lookup maps IPs back to hostnames and surfaces missing or incorrect PTR records. Combine with bulk operations to validate entire IP blocks rather than checking one at a time.
Try Reverse DNSWHOIS and IP ownership for incident response
An unknown IP shows up in your firewall logs or is hitting your API. Who owns it? Which ASN? What network block? DNS Buddy's WHOIS uses RDAP — the structured successor to legacy WHOIS — and supports domains, IP addresses, and ASNs in the same session. Bulk WHOIS lets you resolve ownership for a list of IPs without making individual queries.
Try Bulk WHOIS LookupSubdomain discovery before infrastructure handoffs
Before retiring a domain, migrating a customer, or transferring DNS control, you want to know every subdomain that still resolves. DNS Buddy's subdomain finder uses certificate transparency logs and passive DNS data to enumerate subdomains without active scanning — no noise, no risk of triggering rate limits or security alerts.
Try Subdomain FinderSubnet calculator for IP planning
Network segmentation, VPC planning, firewall rule scoping — all require accurate CIDR math. DNS Buddy's subnet calculator handles network address, broadcast address, host range, and usable host count for any CIDR block. No install needed, works from any browser during an incident call.
Try Subnet CalculatorAll tools at a glance
All free, all in-browser, no account required.
Frequently asked questions
How do I audit DNS records across a fleet of domains?
Use Bulk DNS Lookup. Accepts up to 256 domains at once, any record type, results exportable to CSV. No account needed.
What is FCrDNS and why does it matter?
Forward-confirmed reverse DNS verifies that a host's PTR record and A record agree. Mail servers check this during delivery. Security audits flag mismatches. Some rate-limiting policies enforce it. Bulk FCrDNS validates this across your server inventory in one request.
Can I use DNS Buddy without an account?
Yes. All tools are free with no account required.
Start using DNS Buddy — free, no account needed
Bulk DNS lookup, FCrDNS validation, WHOIS, subnet calculator — all in the browser, no install required.
Need to look up ownership for a mixed list of domains, IPs, and ASNs? Bulk WHOIS Lookup handles all three target types in one batch. New to WHOIS? How to read WHOIS output explains every field.
Also: DNS tools for developers · MxToolbox alternatives · DNSChecker alternatives