uni-koeln.de

Checked 22 October 2026, 00:50 UTC · via 8.8.8.8
!Passed with warnings
22 passed 1 warning 0 failed 6 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, mail1.rrz.uni-koeln.de, noc2.rrz.uni-koeln.de, ns2.netcologne.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
dns-1.dfn.de, mail1.rrz.uni-koeln.de, noc2.rrz.uni-koeln.de, ns2.netcologne.de
NS in the zone
dns-1.dfn.de, mail1.rrz.uni-koeln.de, noc2.rrz.uni-koeln.de, ns2.netcologne.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-
mail1.rrz.uni-koeln.de134.95.100.208AS5520 UNI-KOELN - Universitaet zu Koeln, DE134.95.100.208
noc2.rrz.uni-koeln.de134.95.129.23 2a00:a200:0:50::53AS5520 UNI-KOELN - Universitaet zu Koeln, DE AS5520 UNI-KOELN - Universitaet zu Koeln, DE134.95.129.23 2a00:a200:0:50::53
ns2.netcologne.de194.8.194.71 2001:4dd0:100:1020:53:1:0:2AS8422 NETCOLOGNE - NetCologne Gesellschaft fur Telekommunikation mbH, DE AS8422 NETCOLOGNE - NetCologne Gesellschaft fur Telekommunikation mbH, DE-

Checks

  • ✓ 4 nameservers #6
    Delegated to dns-1.dfn.de, mail1.rrz.uni-koeln.de, noc2.rrz.uni-koeln.de, ns2.netcologne.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: mail1.rrz.uni-koeln.de, noc2.rrz.uni-koeln.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 4 IPv4 /24s and 3 IPv6 /48s.
  • ✓ 3 autonomous systems #11
    The nameservers are spread over: AS5520 (UNI-KOELN - Universitaet zu Koeln, DE): 3 addresses; AS680 (DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE): 2 addresses; AS8422 (NETCOLOGNE - NetCologne Gesellschaft fur Telekommunikation mbH, DE): 2 addresses.
  • 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: mail1.rrz.uni-koeln.de.
    #13

Nameservers

info

7 of 7 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
mail1.rrz.uni-koeln.de 134.95.100.208NOERROR, 11 ms, authoritativenoyes / yesrefusedNone of your business
noc2.rrz.uni-koeln.de 134.95.129.23NOERROR, 11 ms, authoritativenoyes / yesrefusedNone of your business
noc2.rrz.uni-koeln.de 2a00:a200:0:50::53NOERROR, 12 ms, authoritativenoyes / yesrefusedNone of your business
ns2.netcologne.de 194.8.194.71NOERROR, 7 ms, authoritativenoyes / yesrefused-
ns2.netcologne.de 2001:4dd0:100:1020:53:1:0:2NOERROR, 7 ms, authoritativenoyes / yesrefused-

Checks

  • ✓ All respond #14
    All 7 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: dns-1.dfn.de: "0"; mail1.rrz.uni-koeln.de: "None of your business"; noc2.rrz.uni-koeln.de: "None of your business".
    #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 2026102105 · primary noc2.rrz.uni-koeln.de

Found

Primary (MNAME)
noc2.rrz.uni-koeln.de
Contact (RNAME)
hostmaster.uni-koeln.de
Serial
2026102105
Refresh / retry
10800 s / 3600 s
Expire
2419200 s
Negative TTL
3600 s

Serial per nameserver

NameserverSerial
dns-1.dfn.de (193.174.75.50)2026102105
dns-1.dfn.de (2001:638:d:b101::1)2026102105
mail1.rrz.uni-koeln.de (134.95.100.208)2026102105
noc2.rrz.uni-koeln.de (134.95.129.23)2026102105
noc2.rrz.uni-koeln.de (2a00:a200:0:50::53)2026102105
ns2.netcologne.de (194.8.194.71)2026102105
ns2.netcologne.de (2001:4dd0:100:1020:53:1:0:2)2026102105

Checks

  • ✓ Serial 2026102105 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 3h, retry 1h, expire 28d, negative TTL 1h.
  • ✓ Primary is a public nameserver #24
    The primary nameserver noc2.rrz.uni-koeln.de is one of the listed nameservers.
  • ✓ Contact hostmaster@uni-koeln.de #25
    The SOA RNAME hostmaster.uni-koeln.de means hostmaster@uni-koeln.de.
  • ✓ Date-based serial #26
    The serial 2026102105 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

info

19 records at the apex

Found

Read from
193.174.75.50:53
TypeValueTTL
SOAnoc2.rrz.uni-koeln.de. hostmaster.uni-koeln.de. 2026102105 10800 3600 2419200 360010800
NSns2.netcologne.de.10800
NSmail1.rrz.uni-koeln.de.10800
NSdns-1.dfn.de.10800
NSnoc2.rrz.uni-koeln.de.10800
A134.95.81.523600
AAAA2a00:a200:0:2::80300
MX5 uzk-mail-in-v1.rrz.uni-koeln.de.10800
MX5 uzk-mail-in-v2.rrz.uni-koeln.de.10800
TXT"adobe-idp-site-verification=4aec6dd94028767a1112cc5f6e09e54597a8b368698e3090e7942e6ff298e732"300
TXT"MS=ms52477696"300
TXT"google-site-verification=slKdECUuuJ-OuRi4ydQier-7Oj-2Tg_VJyA_kXlUPcU"300
TXT"v=spf1 ip4:134.95.0.0/16 ip4:109.69.68.140 ip6:2a00:a200::/48 include:agenturserver.de ?all"300
TXT"apple-domain-verification=NPadQczkP1xAfjol"300
TXT"MS=3440AC9067529743C07C50066FE452F078A8500F"300
TXT"apple-domain-verification=XscpNBzRkbfzubTd"300
TXT"brevo-code:9aabfa1918b1ee91863be44df6d4b941"300
TXT"apple-domain-verification=fP2uzfO72ptimR1d"300
TXT"cisco-ci-domain-verification=64ff69245d29ac9ceaa0b992ecd76b77594fe0d25edecf3ff8a66d9fd6b2ab2f"300

Checks

  • ✓ TTLs within range #32
    TTLs: A 1h, AAAA 5m, MX 3h, NS 3h. The NS TTL at the parent is 1d and in the zone 3h; 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.
  • 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