tu-dresden.de

.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

adns1.zih.tu-dresden.de, adns2.zih.tu-dresden.de, dns-1.dfn.de, dns-3.dfn.de

Found

Parent zone

de

Delegation from

a.nic.de (194.0.0.53)

NS at the parent

adns1.zih.tu-dresden.de, adns2.zih.tu-dresden.de, dns-1.dfn.de, dns-3.dfn.de

NS in the zone

adns1.zih.tu-dresden.de, adns2.zih.tu-dresden.de, dns-1.dfn.de, dns-3.dfn.de

Checks

• ✓ 4 nameservers #6

  Delegated to adns1.zih.tu-dresden.de, adns2.zih.tu-dresden.de, dns-1.dfn.de, dns-3.dfn.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: adns1.zih.tu-dresden.de, adns2.zih.tu-dresden.de.
• ✓ All names resolve #9

  Every nameserver name has an address and is not an alias.
• i

  One address family in one network

  all IPv6 addresses are in 2001:638:d::/48, while the other address family is spread over several networks.

  #10
• 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): 6 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: adns1.zih.tu-dresden.de, adns2.zih.tu-dresden.de.

  #13

6 of 6 addresses answer authoritatively

Found

Checks

• ✓ All respond #14

  All 6 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.
• i

  Identifying string disclosed

  These nameservers answer version queries with a string that is not a version number: adns1.zih.tu-dresden.de: "0"; adns2.zih.tu-dresden.de: "0"; dns-1.dfn.de: "0"; dns-3.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.

serial 2026100800 · primary pdns1.zih.tu-dresden.de

Found

Primary (MNAME)

pdns1.zih.tu-dresden.de

Contact (RNAME)

hostmaster.tu-dresden.de

Serial

2026100800

Refresh / retry

14400 s / 1800 s

Expire

2764800 s

Negative TTL

1800 s

Serial per nameserver

Checks

• ✓ Serial 2026100800 everywhere #22

  All nameservers serve the same version of the zone.
• ✓ Timers within recommendations #23

  SOA refresh 4h, retry 30m, expire 32d, negative TTL 30m.
• i

  Hidden master

  The primary nameserver pdns1.zih.tu-dresden.de is not listed as a nameserver: a hidden master that only feeds the public secondaries. That is a common setup; make sure it is not reachable for zone transfers from outside.

  #24
• ✓ Contact hostmaster@tu-dresden.de #25

  The SOA RNAME hostmaster.tu-dresden.de means hostmaster@tu-dresden.de.
• ✓ Date-based serial #26

  The serial 2026100800 follows the YYYYMMDDnn convention (2026-10-08).