d-nb.de

Checked 21 October 2026, 22:11 UTC · via 8.8.8.8
✗Problems found
19 passed 2 warnings 1 failed 7 info

Registration

info

.de country-code

Found

TLD
.de (country-code)
ICANN policies apply
no

Checks

  • i
    .de is a country-code TLD (ccTLD)
    Country-code TLD: governed by its local registry under national policy, not by an ICANN contract. Registrar accreditation, dispute resolution and RDAP/WHOIS rules are set by the registry.
    #1
  • ✓ TLD delegated and signed #2
    .de is delegated in the root zone and DNSSEC-signed.
  • i
    Registration data not available
    No registration data via RDAP: the registry of .de offers no RDAP service. Many ccTLD registries don't offer RDAP; check the registry's WHOIS instead.
    #3

Delegation

info

dns-1.dfn.de, ns0.dnb.de, ns1.dnb.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
dns-1.dfn.de, ns0.dnb.de, ns1.dnb.de
NS in the zone
dns-1.dfn.de, ns0.dnb.de, ns1.dnb.de
NameserverAddressesNetwork (AS)Glue
dns-1.dfn.de193.174.75.50 2001:638:d:b101::1AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE-
ns0.dnb.de193.175.100.253AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE193.175.100.253
ns1.dnb.de193.175.100.254AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE193.175.100.254

Checks

  • ✓ 3 nameservers #6
    Delegated to dns-1.dfn.de, ns0.dnb.de, ns1.dnb.de.
  • ✓ Parent and zone agree #7
    The parent delegation and the zone's NS records list the same nameservers.
  • ✓ No glue needed #8
    All nameservers are outside the zone, so no glue records are needed.
  • ✓ All names resolve #9
    Every nameserver name has an address and is not an alias.
  • ✓ Nameservers in different networks #10
    The nameservers are spread over 2 IPv4 /24s and 1 IPv6 /48.
  • i
    All nameservers in one AS
    All nameserver addresses are announced by one network operator (AS680 (DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE): 4 addresses). An outage or attack on that network affects all nameservers; large anycast providers mitigate this, but a secondary DNS provider adds independence.
    #11
  • i
    All nameserver names under .de
    All nameserver names are under one TLD, so a problem with that TLD also makes the nameservers unreachable. Some operators use names under two TLDs for extra resilience.
    #12
  • i
    Partly IPv6
    These nameservers have no IPv6 address: ns0.dnb.de, ns1.dnb.de.
    #13

Nameservers

fail

2 of 4 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
dns-1.dfn.de 193.174.75.50NOERROR, 12 ms, authoritativenoyes / yesrefused0
dns-1.dfn.de 2001:638:d:b101::1NOERROR, 19 ms, authoritativenoyes / yesrefused0
ns0.dnb.de 193.175.100.253no responsenono / no--
ns1.dnb.de 193.175.100.254no responsenono / no--

Checks

  • ✗
    Nameservers not responding
    These addresses did not answer, so resolvers waste time on timeouts: ns0.dnb.de (193.175.100.253): read udp 46.225.38.91:51210->193.175.100.253:53: i/o timeout; ns1.dnb.de (193.175.100.254): read udp 46.225.38.91:48548->193.175.100.254:53: i/o timeout.
    #14
  • ✓ All authoritative #15
    Every responding nameserver answers authoritatively for the zone.
  • ✓ No recursion #16
    The nameservers do not answer recursive queries for other domains.
  • i
    Identifying string disclosed
    These nameservers answer version queries with a string that is not a version number: dns-1.dfn.de: "0".
    #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.

SOA

warn

serial 2022102500 · primary ns.dnb.de

Found

Primary (MNAME)
ns.dnb.de
Contact (RNAME)
hostmaster.dnb.de
Serial
2022102500
Refresh / retry
3600 s / 14400 s
Expire
2419200 s
Negative TTL
3600 s

Serial per nameserver

NameserverSerial
dns-1.dfn.de (193.174.75.50)2022102500
dns-1.dfn.de (2001:638:d:b101::1)2022102500

Checks

  • ✓ Serial 2022102500 everywhere #22
    All nameservers serve the same version of the zone.
  • !
    Unusual SOA timers
    retry 4h should be shorter than refresh 1h. Current values: refresh 1h, retry 4h, expire 28d, negative TTL 1h.
    #23
  • i
    Hidden master (not resolvable)
    The primary nameserver ns.dnb.de is not listed as a nameserver and does not resolve publicly: a hidden master, or a placeholder name. Some tools (e.g. dynamic updates) use MNAME to find the primary.
    #24
  • ✓ Contact hostmaster@dnb.de #25
    The SOA RNAME hostmaster.dnb.de means hostmaster@dnb.de.
  • ✓ Date-based serial #26
    The serial 2022102500 follows the YYYYMMDDnn convention (2022-10-25).

DNSSEC

warn

Not signed

Found

Validated by resolver
no

Checks

  • !
    Not signed
    The zone is not signed with DNSSEC, so answers can be spoofed. Enable DNSSEC at your DNS provider and publish the DS record at your registrar.
    #27

Records

pass

7 records at the apex

Found

Read from
193.174.75.50:53
TypeValueTTL
SOAns.dnb.de. hostmaster.dnb.de. 2022102500 3600 14400 2419200 36003600
NSns0.dnb.de.3600
NSdns-1.dfn.de.3600
NSns1.dnb.de.3600
A193.175.100.2203600
MX10 mail.dnb.de.3600
CAA0 issue "pki.dfn.de"3600

Checks

  • ✓ TTLs within range #32
    TTLs: A 1h, MX 1h, NS 1h. The NS TTL at the parent is 1d and in the zone 1h; resolvers may use either.
  • ✓ 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: pki.dfn.de.