DNSly.io
DNS health check

Check the DNS health of any domain

DNSly follows the delegation from the root zone to every authoritative nameserver, then reviews SOA, mail, web records and DNSSEC. A full report takes about a second.

Examples dnsly.io digitalfyre.com github.com münchen.de
  • Direct nameserver queries
  • No account required
  • Results in about a second
Delegation walk
dnsly.io
.Root zone · a.root-servers.net Referral to io.
io.Registry · nic.io Referral to dnsly.io
dnsly.ioEach nameserver, queried directly
    Querying each nameserver for its SOA serial

    What DNSly checks

    Every report covers the same six areas, from the registry delegation to DNSSEC.

    • Parent delegation

      • Delegation present at the registry
      • Nameservers resolve to addresses
      • Parent and zone NS sets match
      • Glue for in-zone nameservers

    • Nameservers

      • Two to seven servers, per RFC 2182
      • Subnet and network diversity
      • Authoritative answers from each server
      • SOA serial agreement
      • No open recursion

    • SOA record

      • A single SOA record for the zone
      • Primary nameserver in the NS set
      • Serial number
      • Refresh, retry, expire and minimum TTL

    • Mail

      • MX redundancy and valid hostnames
      • No MX target aliased to a CNAME
      • Reverse DNS for every mail address
      • SPF and DMARC policies

    • Web records

      • Addresses for www and the zone apex
      • How www is aliased
      • Publicly routable addresses
      • Reverse DNS where mail shares an address

    • DNSSEC

      • DS record at the parent
      • Chain of trust validates

    From your terminal

    Every report is also available as text. Run it with curl, save it to a file, or use the JSON in your own scripts.

    • curl https://dnsly.io/example.com Report in color, sized for an 80-column terminal
    • curl "https://dnsly.io/example.com?plain" Plain text, for files and pipes
    • curl "https://dnsly.io/api/analyze?domain=example.com" JSON, for scripts and monitoring

    Internationalized names work as typed. The same limit of about 20 reports a minute applies.

    Example terminal report for dnsly.io

    About DNSly

    DNSly.io is a free DNS health check published by DigitalFyre. It reports how a zone is delegated and configured, and flags settings that fall outside RFC guidance or common practice.

    Privacy

    DNSly does not keep the reports it runs. Page visits, including report addresses, are counted with Cloudflare Web Analytics, which does not use cookies or track individual visitors. A theme you choose is saved only in your browser.