duisburg.de

Checked 21 October 2026, 22:15 UTC · via 8.8.8.8
!Passed with warnings
21 passed 3 warnings 0 failed 5 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

warn

ns01.duit.de, ns02.duit.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
ns01.duit.de, ns02.duit.de
NS in the zone
ns01.duit.de, ns02.duit.de
NameserverAddressesNetwork (AS)Glue
ns01.duit.de185.155.188.55AS206141 DVV-GMBH-AS - Duisburger Versorgungs- und Verkehrsgesellschaft mbH, DE185.155.188.55
ns02.duit.de185.155.191.247AS206141 DVV-GMBH-AS - Duisburger Versorgungs- und Verkehrsgesellschaft mbH, DE185.155.191.247

Checks

  • i
    2 nameservers
    Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: ns01.duit.de, ns02.duit.de.
    #6
  • ✓ 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 0 IPv6 /48s.
  • i
    All nameservers in one AS
    All nameserver addresses are announced by one network operator (AS206141 (DVV-GMBH-AS - Duisburger Versorgungs- und Verkehrsgesellschaft mbH, DE): 2 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
  • !
    No IPv6
    None of the nameservers has an IPv6 address, so IPv6-only resolvers can't reach them.
    #13

Nameservers

warn

2 of 2 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
ns01.duit.de 185.155.188.55NOERROR, 8 ms, authoritativenoyes / yesrefused9.16.23-RH
ns02.duit.de 185.155.191.247NOERROR, 9 ms, authoritativenoyes / yesrefused9.16.23-RH

Checks

  • ✓ All respond #14
    All 2 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: ns01.duit.de: "9.16.23-RH"; ns02.duit.de: "9.16.23-RH". 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 2026101504 · primary ns01.duit.de

Found

Primary (MNAME)
ns01.duit.de
Contact (RNAME)
hostmaster.duit.de
Serial
2026101504
Refresh / retry
10800 s / 3600 s
Expire
604800 s
Negative TTL
10800 s

Serial per nameserver

NameserverSerial
ns01.duit.de (185.155.188.55)2026101504
ns02.duit.de (185.155.191.247)2026101504

Checks

  • ✓ Serial 2026101504 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 ns01.duit.de is one of the listed nameservers.
  • ✓ Contact hostmaster@duit.de #25
    The SOA RNAME hostmaster.duit.de means hostmaster@duit.de.
  • ✓ Date-based serial #26
    The serial 2026101504 follows the YYYYMMDDnn convention (2026-10-15).

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

11 records at the apex

Found

Read from
185.155.188.55:53
TypeValueTTL
SOAns01.duit.de. hostmaster.duit.de. 2026101504 10800 3600 604800 108001200
NSns02.duit.de.1200
NSns01.duit.de.1200
A147.28.52.1711200
MX10 mx231.duit.de.1200
MX50 mx20.duit.de.1200
TXT"apple-domain-verification=zB8aKQXCCIaixQl8"1200
TXT"MS=ms26794831"1200
CAA0 iodef "mailto:hostmaster@duit.de"1200
CAA0 issue "comodoca.com"1200
CAA0 issue "letsencrypt.org"1200

Checks

  • ✓ TTLs within range #32
    TTLs: A 20m, MX 20m, NS 20m. The NS TTL at the parent is 1d and in the zone 20m; 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: comodoca.com, letsencrypt.org.