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nlnetlabs.nl

Checked 2026-10-21 21:23 UTC · first added 2026-10-21
!Check could not complete

Domain & DNS

error

26 passed 3 warn 0 failed 1 errors

lookups failed for rdap; results are incomplete

Areas

iRegistration ✓Delegation !Nameservers !SOA iDNSSEC !Records

Problems

  • !
    Software version disclosed
    Nameservers · These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: ns.nlnetlabs.nl: "NSD 4.3.8". Hide or replace the version string.
    #17
  • !
    Unusual SOA timers
    SOA · negative caching TTL (minimum) 4m is outside 5m–1d (RFC 2308 recommends 1–3 hours). Current values: refresh 8h, retry 2h, expire 7d, negative TTL 4m.
    #23
  • !
    Very low TTLs
    Records · These records have a TTL below 5m, causing extra queries and slower lookups: A (4m), AAAA (4m), MX (4m), NS (4m). Low TTLs are useful just before a planned change. The NS TTL at the parent is 1h and in the zone 4m; resolvers may use either.
    #32

Recent checks

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Full report

Domain & DNS report for nlnetlabs.nl ›

Mail

fail

24 passed 5 warn 1 failed

Areas

!SPF ✗DMARC !DKIM ✓DNSSEC ✓MX !TLS iBIMI

Problems

  • ✗
    Policy: none (monitoring only)
    DMARC · DMARC policy is set to 'none', which only monitors but doesn't protect against spoofing. Consider upgrading to 'quarantine' or ideally 'reject'.
    #4
  • !
    1024-bit DKIM key
    DKIM · 1024-bit RSA keys are the minimum and are considered weak today: default (1024 bits). Rotate to a 2048-bit key.
    #23
  • !
    Key in test mode
    DKIM · These keys have t=y, so receivers treat DKIM failures as a test: default. Remove t=y once DKIM works.
    #24
  • !
    Broad IP ranges
    SPF · These ranges authorize tens of thousands of addresses or more: ip6:2a04:b900::/29. Check that you really own and send from all of them.
    #27
  • !
    Not configured
    TLS · MTA-STS is not configured, so other mail servers fall back to unencrypted delivery when TLS fails or is stripped by an attacker. Publish a _mta-sts TXT record and a policy at https://mta-sts.<domain>/.well-known/mta-sts.txt.
    #32
  • !
    Not configured
    TLS · MTA-STS or DANE is used without TLS-RPT, so you get no reports when senders fail to deliver because of TLS problems. Publish _smtp._tls TXT "v=TLSRPTv1; rua=mailto:...".
    #35

Recent checks

✗

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