tu-clausthal.de

Checked 22 October 2026, 00:41 UTC · via 8.8.8.8
!Passed with warnings
23 passed 2 warnings 0 failed 4 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, gomorra.rz.tu-clausthal.de, numerobis.rz.tu-clausthal.de, sodom.rz.tu-clausthal.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
dns-1.dfn.de, gomorra.rz.tu-clausthal.de, numerobis.rz.tu-clausthal.de, sodom.rz.tu-clausthal.de
NS in the zone
dns-1.dfn.de, gomorra.rz.tu-clausthal.de, numerobis.rz.tu-clausthal.de, sodom.rz.tu-clausthal.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-
gomorra.rz.tu-clausthal.de139.174.2.5 2001:638:605:2:1::5AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE139.174.2.5 2001:638:605:2:1::5
numerobis.rz.tu-clausthal.de139.174.33.186 2001:638:605:2021:1::186AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE139.174.33.186 2001:638:605:2021:1::186
sodom.rz.tu-clausthal.de139.174.2.6 2001:638:605:2:1::6AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE139.174.2.6 2001:638:605:2:1::6

Checks

  • ✓ 4 nameservers #6
    Delegated to dns-1.dfn.de, gomorra.rz.tu-clausthal.de, numerobis.rz.tu-clausthal.de, sodom.rz.tu-clausthal.de.
  • ✓ Parent and zone agree #7
    The parent delegation and the zone's NS records list the same nameservers.
  • ✓ Glue present and correct #8
    Glue is published for the nameservers inside the zone: gomorra.rz.tu-clausthal.de, numerobis.rz.tu-clausthal.de, sodom.rz.tu-clausthal.de.
  • ✓ 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 3 IPv4 /24s and 2 IPv6 /48s.
  • 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): 8 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
  • ✓ All reachable over IPv6 #13
    Every nameserver has an IPv6 address.

Nameservers

warn

8 of 8 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
dns-1.dfn.de 193.174.75.50NOERROR, 14 ms, authoritativenoyes / yesrefused0
dns-1.dfn.de 2001:638:d:b101::1NOERROR, 14 ms, authoritativenoyes / yesrefused0
gomorra.rz.tu-clausthal.de 139.174.2.5NOERROR, 8 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.24.04.8-Ubuntu
gomorra.rz.tu-clausthal.de 2001:638:605:2:1::5NOERROR, 9 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.24.04.8-Ubuntu
numerobis.rz.tu-clausthal.de 139.174.33.186NOERROR, 8 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.24.04.8-Ubuntu
numerobis.rz.tu-clausthal.de 2001:638:605:2021:1::186NOERROR, 8 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.24.04.8-Ubuntu
sodom.rz.tu-clausthal.de 139.174.2.6NOERROR, 9 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.24.04.8-Ubuntu
sodom.rz.tu-clausthal.de 2001:638:605:2:1::6NOERROR, 8 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.24.04.8-Ubuntu

Checks

  • ✓ All respond #14
    All 8 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: gomorra.rz.tu-clausthal.de: "9.18.39-0ubuntu0.24.04.8-Ubuntu"; numerobis.rz.tu-clausthal.de: "9.18.39-0ubuntu0.24.04.8-Ubuntu"; sodom.rz.tu-clausthal.de: "9.18.39-0ubuntu0.24.04.8-Ubuntu". 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.

SOA

pass

serial 2026102100 · primary gomorra.rz.tu-clausthal.de

Found

Primary (MNAME)
gomorra.rz.tu-clausthal.de
Contact (RNAME)
hostmaster.tu-clausthal.de
Serial
2026102100
Refresh / retry
10800 s / 3600 s
Expire
604800 s
Negative TTL
10800 s

Serial per nameserver

NameserverSerial
dns-1.dfn.de (193.174.75.50)2026102100
dns-1.dfn.de (2001:638:d:b101::1)2026102100
gomorra.rz.tu-clausthal.de (139.174.2.5)2026102100
gomorra.rz.tu-clausthal.de (2001:638:605:2:1::5)2026102100
numerobis.rz.tu-clausthal.de (139.174.33.186)2026102100
numerobis.rz.tu-clausthal.de (2001:638:605:2021:1::186)2026102100
sodom.rz.tu-clausthal.de (139.174.2.6)2026102100
sodom.rz.tu-clausthal.de (2001:638:605:2:1::6)2026102100

Checks

  • ✓ Serial 2026102100 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 3h, retry 1h, expire 7d, negative TTL 3h.
  • ✓ Primary is a public nameserver #24
    The primary nameserver gomorra.rz.tu-clausthal.de is one of the listed nameservers.
  • ✓ Contact hostmaster@tu-clausthal.de #25
    The SOA RNAME hostmaster.tu-clausthal.de means hostmaster@tu-clausthal.de.
  • ✓ Date-based serial #26
    The serial 2026102100 follows the YYYYMMDDnn convention (2026-10-21).

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

21 records at the apex

Found

Read from
193.174.75.50:53
TypeValueTTL
SOAgomorra.rz.tu-clausthal.de. hostmaster.tu-clausthal.de. 2026102100 10800 3600 604800 10800172800
NSsodom.rz.tu-clausthal.de.604800
NSdns-1.dfn.de.604800
NSnumerobis.rz.tu-clausthal.de.604800
NSgomorra.rz.tu-clausthal.de.604800
A139.174.33.138172800
AAAA2001:638:605:2021:1::138172800
MX10 a1071.mx.srv.dfn.de.172800
MX10 b1071.mx.srv.dfn.de.172800
MX10 c1071.mx.srv.dfn.de.172800
TXT"adobe-idp-site-verification=38688460cb4ba30bc042ced2430ed03f44270bac41a2a64b21342f9ffb63bb1d"172800
TXT"atlassian-domain-verification=hDE0/IEe77icGFTKS41l9lsabbyEkPxzY1ba4z10rdbxDu7qtpTiLDp5YEASK18e"172800
TXT"HARICA-sdePtmQ6dkJtSeFc1jC"172800
TXT"v=spf1 include:_spf.tu-clausthal.de ~all"172800
TXT"anthropic-domain-verification-cm82mv=OP9IB5Gu3aby80iXVBBc4t0PB"172800
TXT"google-site-verification=bOtQbT2xPQ-o2c7xCEkBVaFqClmjHIHajL247zmgAzM"172800
TXT"dell-technologies-domain-verification=tu-clausthal.de_103d37c3-bf9d-416d-8b6a-640a9f01eb88_1702544292"172800
TXT"ZOOM_verify_lE_-Ou_ISn2nIRLBwqo3ZA"172800
CAA0 issue "harica.gr"172800
CAA0 issue "letsencrypt.org"172800
CAA0 issue "pki.dfn.de"172800

Checks

  • ✓ TTLs within range #32
    TTLs: A 2d, AAAA 2d, MX 2d, NS 7d. The NS TTL at the parent is 1d and in the zone 7d; 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: harica.gr, letsencrypt.org, pki.dfn.de.