uni-greifswald.de

Checked 22 October 2026, 00:50 UTC · via 8.8.8.8
!Passed with warnings
23 passed 4 warnings 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

warn

dns1.uni-greifswald.de, dns2.uni-greifswald.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
dns1.uni-greifswald.de, dns2.uni-greifswald.de
NS in the zone
dns1.uni-greifswald.de, dns2.uni-greifswald.de
NameserverAddressesNetwork (AS)Glue
dns1.uni-greifswald.de141.53.10.4AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE141.53.10.4
dns2.uni-greifswald.de141.53.10.5AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE141.53.10.5

Checks

  • i
    2 nameservers
    Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: dns1.uni-greifswald.de, dns2.uni-greifswald.de.
    #6
  • ✓ 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: dns1.uni-greifswald.de, dns2.uni-greifswald.de.
  • ✓ All names resolve #9
    Every nameserver name has an address and is not an alias.
  • !
    Nameservers in one network
    all IPv4 addresses are in 141.53.10.0/24. A single network failure takes all nameservers down; RFC 2182 recommends topologically separate networks (anycast setups are an exception).
    #10
  • 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): 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
dns1.uni-greifswald.de 141.53.10.4NOERROR, 17 ms, authoritativenoyes / yesrefused9.20.29-1~deb13u1-Debian
dns2.uni-greifswald.de 141.53.10.5NOERROR, 17 ms, authoritativenoyes / yesrefused9.20.29-1~deb13u1-Debian

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: dns1.uni-greifswald.de: "9.20.29-1~deb13u1-Debian"; dns2.uni-greifswald.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

warn

serial 2026102148 · primary dns1.uni-greifswald.de

Found

Primary (MNAME)
dns1.uni-greifswald.de
Contact (RNAME)
hostmaster.uni-greifswald.de
Serial
2026102148
Refresh / retry
86400 s / 7200 s
Expire
1814400 s
Negative TTL
172800 s

Serial per nameserver

NameserverSerial
dns1.uni-greifswald.de (141.53.10.4)2026102148
dns2.uni-greifswald.de (141.53.10.5)2026102148

Checks

  • ✓ Serial 2026102148 everywhere #22
    All nameservers serve the same version of the zone.
  • !
    Unusual SOA timers
    negative caching TTL (minimum) 2d is outside 5m–1d (RFC 2308 recommends 1–3 hours). Current values: refresh 1d, retry 2h, expire 21d, negative TTL 2d.
    #23
  • ✓ Primary is a public nameserver #24
    The primary nameserver dns1.uni-greifswald.de is one of the listed nameservers.
  • ✓ Contact hostmaster@uni-greifswald.de #25
    The SOA RNAME hostmaster.uni-greifswald.de means hostmaster@uni-greifswald.de.
  • ✓ Date-based serial #26
    The serial 2026102148 follows the YYYYMMDDnn convention (2026-10-21).

DNSSEC

info

Signed, DS published at parent

Found

Validated by resolver
yes
Denial of existence
NSEC
Signatures valid until
20 November 2026

DS at the parent

Key tagAlgorithmDigestMatches a key
49364ECDSAP384SHA384 (14)SHA256 A6AA4660BB798A10…yes

DNSKEY in the zone

Key tagRoleAlgorithm
49364KSK (257)ECDSAP384SHA384 (14)
30099ZSK (256)ECDSAP384SHA384 (14)

Checks

  • ✓ Signed and validated #27
    The zone is signed, the parent publishes a DS record, and the resolver validates the answers.
  • ✓ DS matches a key #28
    The DS record at the parent matches a key in the zone: key tag 49364 (SHA256).
  • ✓ Modern algorithms #29
    Key algorithms: ECDSAP384SHA384 (14).
  • ✓ Signatures valid until 2026-11-20 #30
    The earliest DNSKEY/SOA signature expires at 2026-11-20 23:11 UTC.
  • i
    NSEC
    The zone uses NSEC, so its full contents can be listed by walking the NSEC chain. That is fine unless the names are sensitive.
    #31

Records

pass

13 records at the apex

Found

Read from
141.53.10.4:53
TypeValueTTL
SOAdns1.uni-greifswald.de. hostmaster.uni-greifswald.de. 2026102148 86400 7200 1814400 172800172800
NSdns1.uni-greifswald.de.3600
NSdns2.uni-greifswald.de.3600
A141.53.15.1203600
MX10 mx1.uni-greifswald.de.3600
MX10 mx2.uni-greifswald.de.3600
TXT"MS=D352C1C447E34E6ABB93F23AB47CA72119C1DBA2"3600
TXT"v=spf1 ip4:141.53.10.0/24 mx ~all"3600
TXT"adobe-idp-site-verification=042205e3e922a4623f83799e145fd8958337cf50c13cc340d17f472cc8b6fd88"3600
CAA0 issuewild ";"3600
CAA0 issuemail "harica.gr"3600
CAA0 issue "harica.gr"3600
CAA0 issue "letsencrypt.org"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: none (issuance forbidden), harica.gr, letsencrypt.org.