uniklinik-duesseldorf.de

Checked 22 October 2026, 00:50 UTC · via 8.8.8.8
!Passed with warnings
21 passed 1 warning 0 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

ns1.arcor-ip.de, ns2.arcor-ip.de, ns3.arcor-ip.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
ns1.arcor-ip.de, ns2.arcor-ip.de, ns3.arcor-ip.de
NS in the zone
ns1.arcor-ip.de, ns2.arcor-ip.de, ns3.arcor-ip.de
NameserverAddressesNetwork (AS)Glue
ns1.arcor-ip.de145.253.2.144 2a01:860:0:202::53AS3209 VODANET - Vodafone GmbH, DE AS3209 VODANET - Vodafone GmbH, DE145.253.2.144 2a01:860:0:202::53
ns2.arcor-ip.de145.253.3.16 2a01:860:0:203::53AS3209 VODANET - Vodafone GmbH, DE AS3209 VODANET - Vodafone GmbH, DE145.253.3.16 2a01:860:0:203::53
ns3.arcor-ip.de145.253.3.20 2a01:860:0:204::53AS3209 VODANET - Vodafone GmbH, DE AS3209 VODANET - Vodafone GmbH, DE145.253.3.20 2a01:860:0:204::53

Checks

  • ✓ 3 nameservers #6
    Delegated to ns1.arcor-ip.de, ns2.arcor-ip.de, ns3.arcor-ip.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.
  • i
    One address family in one network
    all IPv6 addresses are in 2a01:860::/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 (AS3209 (VODANET - Vodafone GmbH, 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
  • ✓ All reachable over IPv6 #13
    Every nameserver has an IPv6 address.

Nameservers

pass

6 of 6 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
ns1.arcor-ip.de 145.253.2.144NOERROR, 3 ms, authoritativenoyes / yesrefused-
ns1.arcor-ip.de 2a01:860:0:202::53NOERROR, 4 ms, authoritativenoyes / yesrefused-
ns2.arcor-ip.de 145.253.3.16NOERROR, 13 ms, authoritativenoyes / yesrefused-
ns2.arcor-ip.de 2a01:860:0:203::53NOERROR, 13 ms, authoritativenoyes / yesrefused-
ns3.arcor-ip.de 145.253.3.20NOERROR, 9 ms, authoritativenoyes / yesrefused-
ns3.arcor-ip.de 2a01:860:0:204::53NOERROR, 9 ms, authoritativenoyes / yesrefused-

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.
  • ✓ No version disclosed #17
    The nameservers don't reveal their software version.
  • ✓ 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 2026092700 · primary ns1.arcor-ip.de

Found

Primary (MNAME)
ns1.arcor-ip.de
Contact (RNAME)
hostmaster.adm.arcor.net
Serial
2026092700
Refresh / retry
28800 s / 14400 s
Expire
1814400 s
Negative TTL
7200 s

Serial per nameserver

NameserverSerial
ns1.arcor-ip.de (145.253.2.144)2026092700
ns1.arcor-ip.de (2a01:860:0:202::53)2026092700
ns2.arcor-ip.de (145.253.3.16)2026092700
ns2.arcor-ip.de (2a01:860:0:203::53)2026092700
ns3.arcor-ip.de (145.253.3.20)2026092700
ns3.arcor-ip.de (2a01:860:0:204::53)2026092700

Checks

  • ✓ Serial 2026092700 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 8h, retry 4h, expire 21d, negative TTL 2h.
  • ✓ Primary is a public nameserver #24
    The primary nameserver ns1.arcor-ip.de is one of the listed nameservers.
  • ✓ Contact hostmaster@adm.arcor.net #25
    The SOA RNAME hostmaster.adm.arcor.net means hostmaster@adm.arcor.net.
  • ✓ Date-based serial #26
    The serial 2026092700 follows the YYYYMMDDnn convention (2026-09-27).

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

info

10 records at the apex

Found

Read from
145.253.2.144:53
TypeValueTTL
SOAns1.arcor-ip.de. hostmaster.adm.arcor.net. 2026092700 28800 14400 1814400 72003600
NSns1.arcor-ip.de.3600
NSns3.arcor-ip.de.3600
NSns2.arcor-ip.de.3600
A185.57.241.83600
MX10 mail1-ukd.med.uni-duesseldorf.de.3600
TXT"HARICA-AGreXxK1FRaOZPDh15f"3600
TXT"linkedin-site-verification=199c1914-3ba1-4968-bb9e-8d8767f6adb1"3600
TXT"MS=ms44826508"3600
TXT"yxmsy87dq80h8dp01qp1y8bdpc7yym3k"3600

Checks

  • ✓ TTLs within range #32
    TTLs: A 10m, 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.
  • i
    Wildcard record
    A random name under the zone resolves, so there is a wildcard (*) record. Typos and non-existent hosts resolve too, which can confuse mail and certificate checks.
    #34
  • i
    No CAA records
    Without CAA records any certificate authority may issue certificates for this domain. A CAA record limits issuance to the CAs you use.
    #35