security.nl

10 of 10 addresses answer authoritatively

Found

Checks

• ✓ All respond #14

  All 10 nameserver addresses answered.
• ✓ All authoritative #15

  Every responding nameserver answers authoritatively for the zone.
• ✓ No recursion #16

  The nameservers do not answer recursive queries for other domains.
• !

  Software version disclosed

  These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: ns1.certifiedsecure.com: "PowerDNS Authoritative Server 5.1.4 (built Aug 5 2026 13:12:37 by root@localhost)"; ns2.certifiedsecure.com: "PowerDNS Authoritative Server 5.1.4 (built Aug 5 2026 13:12:37 by root@localhost)"; ns3.certifiedsecure.com: "PowerDNS Authoritative Server 5.1.5 (built Oct 7 2026 06:12:54 by root@localhost)"; ns4.certifiedsecure.com: "PowerDNS Authoritative Server 5.1.5 (built Oct 7 2026 06:12:54 by root@localhost)". Hide or replace the version string.

  #17
• ✓ Zone transfers refused #18

  No nameserver allows a zone transfer to the public.
• ✓ TCP supported #19

  All nameservers answer over TCP.
• ✓ EDNS supported #20

  All nameservers support EDNS(0).
• ✓ Public addresses #21

  All nameserver addresses are publicly routable.

serial 2021042101 · primary ns3.certifiedsecure.com

Found

Primary (MNAME)

ns3.certifiedsecure.com

Contact (RNAME)

dnsmaster.certifiedsecure.com

Serial

2021042101

Refresh / retry

300 s / 1800 s

Expire

2419200 s

Negative TTL

300 s

Serial per nameserver

Checks

• ✓ Serial 2021042101 everywhere #22

  All nameservers serve the same version of the zone.
• !

  Unusual SOA timers

  refresh 5m is outside 20m–1d; retry 30m should be shorter than refresh 5m. Current values: refresh 5m, retry 30m, expire 28d, negative TTL 5m.

  #23
• ✓ Primary is a public nameserver #24

  The primary nameserver ns3.certifiedsecure.com is one of the listed nameservers.
• ✓ Contact dnsmaster@certifiedsecure.com #25

  The SOA RNAME dnsmaster.certifiedsecure.com means dnsmaster@certifiedsecure.com.
• ✓ Date-based serial #26

  The serial 2021042101 follows the YYYYMMDDnn convention (2021-04-21).

Signed, DS published at parent

Found

Validated by resolver

yes

Denial of existence

NSEC3

NSEC3

100 iterations, 8-byte salt

Signatures valid until

18 September 2027

DS at the parent

DNSKEY in the zone

Checks

• ✓ Signed and validated #27

  The zone is signed, the parent publishes a DS record, and the resolver validates the answers.
• ✓ DS matches a key #28

  The DS record at the parent matches a key in the zone: key tag 45258 (SHA256).
• ✓ Modern algorithms #29

  Key algorithms: ECDSAP256SHA256 (13).
• ✓ Signatures valid until 2027-09-18 #30

  The earliest DNSKEY/SOA signature expires at 2027-09-18 10:41 UTC.
• !

  NSEC3 with extra iterations or salt

  NSEC3 uses 100 iterations and a 8-byte salt. RFC 9276 recommends 0 iterations and no salt: extra iterations cost resolvers CPU and add no real protection, and some validators treat high counts as insecure.

  #31

16 records at the apex

Found

Read from

195.135.195.195:53

Checks

• !

  Very low TTLs

  These records have a TTL below 5m, causing extra queries and slower lookups: A (1m), MX (1m). Low TTLs are useful just before a planned change. The NS TTL at the parent is 1h and in the zone 5m; resolvers may use either.

  #32
• ✓ No CNAME at the apex #33

  The zone apex has no CNAME record.
• ✓ No wildcard #34

  Names that don't exist return NXDOMAIN.
• ✓ CAA restricts issuance #35

  Certificates may be issued by: digicert.com.