geomar.de

Checked 21 October 2026, 22:40 UTC · via 8.8.8.8
!Passed with warnings
20 passed 3 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

dns-1.dfn.de, dns-2.dfn.de, dns-3.dfn.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
dns-1.dfn.de, dns-2.dfn.de, dns-3.dfn.de
NS in the zone
dns-1.dfn.de, dns-2.dfn.de, dns-3.dfn.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-
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-
dns-3.dfn.de193.174.75.58 2001:638:d:b103::1AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE-

Checks

  • ✓ 3 nameservers #6
    Delegated to dns-1.dfn.de, dns-2.dfn.de, dns-3.dfn.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 one network
    all IPv4 addresses are in 193.174.75.0/24; all IPv6 addresses are in 2001:638:d::/48. 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): 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

info

6 of 6 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
dns-1.dfn.de 193.174.75.50NOERROR, 12 ms, authoritativenoyes / yesrefused0
dns-1.dfn.de 2001:638:d:b101::1NOERROR, 17 ms, authoritativenoyes / yesrefused0
dns-2.dfn.de 193.174.75.54NOERROR, 7 ms, authoritativenoyes / yesrefused0
dns-2.dfn.de 2001:638:d:b102::1NOERROR, 11 ms, authoritativenoyes / yesrefused0
dns-3.dfn.de 193.174.75.58NOERROR, 8 ms, authoritativenoyes / yesrefused0
dns-3.dfn.de 2001:638:d:b103::1NOERROR, 10 ms, authoritativenoyes / yesrefused0

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.
  • i
    Identifying string disclosed
    These nameservers answer version queries with a string that is not a version number: dns-1.dfn.de: "0"; dns-2.dfn.de: "0"; dns-3.dfn.de: "0".
    #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 2021073521 · primary ddi01.geomar.de

Found

Primary (MNAME)
ddi01.geomar.de
Contact (RNAME)
hostmaster.geomar.de
Serial
2021073521
Refresh / retry
21600 s / 3600 s
Expire
604800 s
Negative TTL
172800 s

Serial per nameserver

NameserverSerial
dns-1.dfn.de (193.174.75.50)2021073521
dns-1.dfn.de (2001:638:d:b101::1)2021073521
dns-2.dfn.de (193.174.75.54)2021073521
dns-2.dfn.de (2001:638:d:b102::1)2021073521
dns-3.dfn.de (193.174.75.58)2021073521
dns-3.dfn.de (2001:638:d:b103::1)2021073521

Checks

  • ✓ Serial 2021073521 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 6h, retry 1h, expire 7d, negative TTL 2d.
    #23
  • i
    Hidden master
    The primary nameserver ddi01.geomar.de is not listed as a nameserver: a hidden master that only feeds the public secondaries. That is a common setup; make sure it is not reachable for zone transfers from outside.
    #24
  • ✓ Contact hostmaster@geomar.de #25
    The SOA RNAME hostmaster.geomar.de means hostmaster@geomar.de.
  • ✓ Timestamp serial #26
    The serial 2021073521 is a Unix timestamp (2034-01-17 01:18 UTC).

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

28 records at the apex

Found

Read from
193.174.75.50:53
TypeValueTTL
SOAddi01.geomar.de. hostmaster.geomar.de. 2021073521 21600 3600 604800 17280014400
NSdns-1.dfn.de.14400
NSdns-3.dfn.de.14400
NSdns-2.dfn.de.14400
A37.120.188.3314400
MX10 a1501.mx.srv.dfn.de.14400
MX10 c1501.mx.srv.dfn.de.14400
MX10 b1501.mx.srv.dfn.de.14400
TXT"atlassian-domain-verification=bCagtWOUSD0ttMja0ntm/MmsGf98lFeJtCGSaMU6Advat/t5JEUWOk0Je1689a/V"3600
TXT"langdock-verify=t9tpmGNMB0H0oVnT-e01Es4dVClqM4wwqBA6faDoVKY"3600
TXT"google-site-verification=i9-6iGz8AmXaRwlSCn82naXaJR0YAtUU4ADmZGP2ba4"3600
TXT"sophos-domain-verification=8a0454049e337100e481491e2dfb6f0023b7c9b8ddcf35b1069b9c0a47350aa5"3600
TXT"v=spf1 mx ip4:212.201.155.0/24 include:_spf.o150.mx.srv.dfn.de include:spf.protection.outlook.com include:spf.crsend.com ~all"3600
TXT"cisco-ci-domain-verification=5d96aceb5bf87289cfe2b3ec00930a58f9355979335ea8a3457bd3572c137d0c"3600
TXT"MS=ms60749358"3600
TXT"HARICA-VwJe7eLOB0cQV1wos2f"3600
TXT"academiccloud-site-verification=qRtcx7rPFJN42Xyq4RF8tZWNQ"3600
TXT"adobe-idp-site-verification=5f9bfba5ff21f4584d98b3d7445d6f2ba57e7e0d00124f97145b6efdbe1f8026"3600
TXT"miro-verification=36f7bedca5a240b6250d0f10e651bdb243ae2a9b"3600
CAA0 issuewild "harica.gr"14400
CAA0 iodef "mailto:pki@geomar.de"14400
CAA0 issue "harica.gr"14400
CAA0 issue "letsencrypt.org"14400
CAA0 issue "sectigo.com"14400
CAA0 issue "pki.dfn.de"14400
CAA0 issuewild "sectigo.com"14400
CAA0 issuewild "pki.dfn.de"14400
CAA0 issuewild "letsencrypt.org"14400

Checks

  • ✓ TTLs within range #32
    TTLs: A 4h, MX 4h, NS 4h. The NS TTL at the parent is 1d and in the zone 4h; 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: harica.gr, letsencrypt.org, sectigo.com, pki.dfn.de.