NS/SOA Consistency Checker

Verify DNS nameserver and SOA (Start of Authority) record consistency. Check that all listed nameservers resolve correctly and analyze SOA parameters for proper DNS configuration.

NS/SOA Examples

NS/SOA Check

Understanding NS and SOA Records

NS (Name Server) Records

NS records specify which name servers are authoritative for a domain. All listed nameservers should:

  • Resolve to valid IP addresses
  • Be reachable and responsive
  • Serve consistent zone data
  • Be geographically distributed for redundancy

SOA (Start of Authority)

The SOA record contains administrative information about the zone:

  • Serial: Version number for zone changes
  • Refresh: How often secondaries check for updates
  • Retry: Wait time before retrying failed transfers
  • Expire: When to stop serving stale data
  • Minimum: Default negative response TTL

Recommended Values

Refresh: 1-24 hours (3600-86400s)
Retry: 10-60 minutes (600-3600s)
Expire: 1-4 weeks (604800-2419200s)
Minimum: 5 minutes to 1 hour (300-3600s)

Common Issues

  • Unreachable nameservers: Can cause resolution failures
  • Inconsistent data: Different responses from different NS
  • Wrong SOA values: Too aggressive or too conservative timing
  • Serial number issues: Outdated or incorrect format