uni-luebeck.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

deneb.dfn.de, dns01.uni-luebeck.de, dns02.uni-luebeck.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
deneb.dfn.de, dns01.uni-luebeck.de, dns02.uni-luebeck.de
NS in the zone
deneb.dfn.de, dns01.uni-luebeck.de, dns02.uni-luebeck.de
NameserverAddressesNetwork (AS)Glue
deneb.dfn.de192.76.176.9 2001:638:800:1::9AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE-
dns01.uni-luebeck.de141.83.100.100AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE141.83.100.100
dns02.uni-luebeck.de141.83.99.99AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE141.83.99.99

Checks

  • ✓ 3 nameservers #6
    Delegated to deneb.dfn.de, dns01.uni-luebeck.de, dns02.uni-luebeck.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: dns01.uni-luebeck.de, dns02.uni-luebeck.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 3 IPv4 /24s and 1 IPv6 /48.
  • 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): 4 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: dns01.uni-luebeck.de, dns02.uni-luebeck.de.
    #13

Nameservers

info

4 of 4 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
deneb.dfn.de 192.76.176.9NOERROR, 14 ms, authoritativenoyes / yesrefused0
deneb.dfn.de 2001:638:800:1::9NOERROR, 14 ms, authoritativenoyes / yesrefused0
dns01.uni-luebeck.de 141.83.100.100NOERROR, 18 ms, authoritativenoyes / yesrefusedhurz, who care about versions ;)
dns02.uni-luebeck.de 141.83.99.99NOERROR, 20 ms, authoritativenoyes / yesrefusedhurz, who care about versions ;)

Checks

  • ✓ All respond #14
    All 4 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: deneb.dfn.de: "0"; dns01.uni-luebeck.de: "hurz, who care about versions ;)"; dns02.uni-luebeck.de: "hurz, who care about versions ;)".
    #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 2026101900 · primary dns01.uni-luebeck.de

Found

Primary (MNAME)
dns01.uni-luebeck.de
Contact (RNAME)
hostmaster.uni-luebeck.de
Serial
2026101900
Refresh / retry
43200 s / 36000 s
Expire
604800 s
Negative TTL
86400 s

Serial per nameserver

NameserverSerial
deneb.dfn.de (192.76.176.9)2026101900
deneb.dfn.de (2001:638:800:1::9)2026101900
dns01.uni-luebeck.de (141.83.100.100)2026101900
dns02.uni-luebeck.de (141.83.99.99)2026101900

Checks

  • ✓ Serial 2026101900 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 12h, retry 10h, expire 7d, negative TTL 1d.
  • ✓ Primary is a public nameserver #24
    The primary nameserver dns01.uni-luebeck.de is one of the listed nameservers.
  • ✓ Contact hostmaster@uni-luebeck.de #25
    The SOA RNAME hostmaster.uni-luebeck.de means hostmaster@uni-luebeck.de.
  • ✓ Date-based serial #26
    The serial 2026101900 follows the YYYYMMDDnn convention (2026-10-19).

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

22 records at the apex

Found

Read from
192.76.176.9:53
TypeValueTTL
SOAdns01.uni-luebeck.de. hostmaster.uni-luebeck.de. 2026101900 43200 36000 604800 864003600
NSdns01.uni-luebeck.de.3600
NSdns02.uni-luebeck.de.3600
NSdeneb.dfn.de.3600
A141.83.104.2333600
MX10 ip3.rz.uni-luebeck.de.3600
MX10 ip1.rz.uni-luebeck.de.3600
MX10 ip2.rz.uni-luebeck.de.3600
TXT"duo_sso_verification=AsJZA51NXp3m7VxmYqOwIN7uFiPlnbDpfXhqx9CUu224NpkGpDrzS4ltcUZJUoe4"3600
TXT"abuseipdb-verification=i64mBn4m"3600
TXT"MS=ms72522114"3600
TXT"v=spf1 +mx ip4:141.83.100.71/32 ip4:141.83.100.72/32 ip4:141.83.100.74/32 ip4:141.83.100.70/32 ip4:141.83.100.95/32 -all"3600
TXT"_telesec-domain-validation=342549_2025-11-17_0avRBStwKakztrsVUsWy6YDlKkgMuqReCtMVGgmetUq2gSIG2h"3600
TXT"HARICA-YuszeI4VhYAa8EdKMQM"3600
TXT"intersight=5107a85b98acbf3094791e872cddccf869e4b51fa601b6d1c94f5c131b6a6b4c"3600
TXT"google-site-verification=Q2TqXP3rH_lG9HutkGjsGiWZ8gLZcqard4TJH3-Ciu0"3600
TXT"ciscocidomainverification=a99ff3d68626e857357c48d957a15b58ec4fadf87dda4c4db1f1d692215d27d"3600
TXT"academiccloud-site-verification=jyKQrEZXZ8n7Q6AMtZf7rDrfw"3600
CAA0 issue "pki.dfn.de"3600
CAA0 issue "harica.gr"3600
CAA0 issue "telesec.de"3600
CAA0 issue "sectigo.com"3600

Checks

  • ✓ TTLs within range #32
    TTLs: A 1h, 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.
  • ✓ No wildcard #34
    Names that don't exist return NXDOMAIN.
  • ✓ CAA restricts issuance #35
    Certificates may be issued by: pki.dfn.de, harica.gr, telesec.de, sectigo.com.