uni-duisburg.de

Checked 22 October 2026, 00:50 UTC · via 8.8.8.8
!Passed with warnings
22 passed 2 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

info

dns-2.dfn.de, ns1.uni-duisburg-essen.de, ns2.uni-duisburg-essen.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
dns-2.dfn.de, ns1.uni-duisburg-essen.de, ns2.uni-duisburg-essen.de
NS in the zone
dns-2.dfn.de, ns1.uni-duisburg-essen.de, ns2.uni-duisburg-essen.de
NameserverAddressesNetwork (AS)Glue
dns-2.dfn.de193.174.75.54 2001:638:d:b102::1AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE-
ns1.uni-duisburg-essen.de132.252.184.130 2001:638:501:1::53AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE132.252.184.130 2001:638:501:1::53
ns2.uni-duisburg-essen.de132.252.184.140 2001:638:501:2::53AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE132.252.184.140 2001:638:501:2::53

Checks

  • ✓ 3 nameservers #6
    Delegated to dns-2.dfn.de, ns1.uni-duisburg-essen.de, ns2.uni-duisburg-essen.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 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): 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

warn

6 of 6 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
dns-2.dfn.de 193.174.75.54NOERROR, 7 ms, authoritativenoyes / yesrefused0
dns-2.dfn.de 2001:638:d:b102::1NOERROR, 6 ms, authoritativenoyes / yesrefused0
ns1.uni-duisburg-essen.de 132.252.184.130NOERROR, 7 ms, authoritativenoyes / yesrefused9.20.29-1~deb13u1-Debian
ns1.uni-duisburg-essen.de 2001:638:501:1::53NOERROR, 7 ms, authoritativenoyes / yesrefused9.20.29-1~deb13u1-Debian
ns2.uni-duisburg-essen.de 132.252.184.140NOERROR, 7 ms, authoritativenoyes / yesrefused9.20.29-1~deb13u1-Debian
ns2.uni-duisburg-essen.de 2001:638:501:2::53NOERROR, 7 ms, authoritativenoyes / yesrefused9.20.29-1~deb13u1-Debian

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.
  • !
    Software version disclosed
    These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: ns1.uni-duisburg-essen.de: "9.20.29-1~deb13u1-Debian"; ns2.uni-duisburg-essen.de: "9.20.29-1~deb13u1-Debian". 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 2026100100 · primary ns1.uni-duisburg-essen.de

Found

Primary (MNAME)
ns1.uni-duisburg-essen.de
Contact (RNAME)
netadm.uni-duisburg-essen.de
Serial
2026100100
Refresh / retry
14400 s / 3600 s
Expire
1209600 s
Negative TTL
600 s

Serial per nameserver

NameserverSerial
dns-2.dfn.de (193.174.75.54)2026100100
dns-2.dfn.de (2001:638:d:b102::1)2026100100
ns1.uni-duisburg-essen.de (132.252.184.130)2026100100
ns1.uni-duisburg-essen.de (2001:638:501:1::53)2026100100
ns2.uni-duisburg-essen.de (132.252.184.140)2026100100
ns2.uni-duisburg-essen.de (2001:638:501:2::53)2026100100

Checks

  • ✓ Serial 2026100100 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 4h, retry 1h, expire 14d, negative TTL 10m.
  • ✓ Primary is a public nameserver #24
    The primary nameserver ns1.uni-duisburg-essen.de is one of the listed nameservers.
  • ✓ Contact netadm@uni-duisburg-essen.de #25
    The SOA RNAME netadm.uni-duisburg-essen.de means netadm@uni-duisburg-essen.de.
  • ✓ Date-based serial #26
    The serial 2026100100 follows the YYYYMMDDnn convention (2026-10-01).

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

8 records at the apex

Found

Read from
193.174.75.54:53
TypeValueTTL
SOAns1.uni-duisburg-essen.de. netadm.uni-duisburg-essen.de. 2026100100 14400 3600 1209600 60086400
NSdns-2.dfn.de.86400
NSns1.uni-duisburg-essen.de.86400
NSns2.uni-duisburg-essen.de.86400
MX10 mx-serv4.uni-due.de.86400
MX10 mx-serv3.uni-due.de.86400
MX10 mx-serv5.uni-due.de.86400
TXT"v=spf1 include:uni-due.de ~all"86400

Checks

  • ✓ TTLs within range #32
    TTLs: MX 1d, NS 1d.
  • ✓ No CNAME at the apex #33
    The zone apex has no CNAME record.
  • ✓ No wildcard #34
    Names that don't exist return NXDOMAIN.
  • 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