fzi.de

Checked 21 October 2026, 22:32 UTC · via 8.8.8.8
!Passed with warnings
23 passed 1 warning 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

fzi-dc-05.fzi.de, fzi-dc-06.fzi.de, fzi-dc-07.fzi.de, nsb0.schlundtech.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
fzi-dc-05.fzi.de, fzi-dc-06.fzi.de, fzi-dc-07.fzi.de, nsb0.schlundtech.de
NS in the zone
fzi-dc-05.fzi.de, fzi-dc-06.fzi.de, fzi-dc-07.fzi.de, nsb0.schlundtech.de
NameserverAddressesNetwork (AS)Glue
fzi-dc-05.fzi.de141.21.0.11 2001:67c:2acc:10:141:21:0:11AS205046 FZI-AS-1 - FZI Forschungszentrum Informatik, DE AS205046 FZI-AS-1 - FZI Forschungszentrum Informatik, DE141.21.0.11 2001:67c:2acc:10:141:21:0:11
fzi-dc-06.fzi.de141.21.0.12 2001:67c:2acc:10:141:21:0:12AS205046 FZI-AS-1 - FZI Forschungszentrum Informatik, DE AS205046 FZI-AS-1 - FZI Forschungszentrum Informatik, DE141.21.0.12 2001:67c:2acc:10:141:21:0:12
fzi-dc-07.fzi.de141.21.0.13 2001:67c:2acc:10:141:21:0:13AS205046 FZI-AS-1 - FZI Forschungszentrum Informatik, DE AS205046 FZI-AS-1 - FZI Forschungszentrum Informatik, DE141.21.0.13 2001:67c:2acc:10:141:21:0:13
nsb0.schlundtech.de185.132.35.227 2607:f1c0:fe:53:185:132:35:227AS15418 IONOS-ANYCAST - Fasthosts Internet Limited, GB AS15418 IONOS-ANYCAST - Fasthosts Internet Limited, GB-

Checks

  • ✓ 4 nameservers #6
    Delegated to fzi-dc-05.fzi.de, fzi-dc-06.fzi.de, fzi-dc-07.fzi.de, nsb0.schlundtech.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: fzi-dc-05.fzi.de, fzi-dc-06.fzi.de, fzi-dc-07.fzi.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 2 IPv4 /24s and 2 IPv6 /48s.
  • ✓ 2 autonomous systems #11
    The nameservers are spread over: AS15418 (IONOS-ANYCAST - Fasthosts Internet Limited, GB): 2 addresses; AS205046 (FZI-AS-1 - FZI Forschungszentrum Informatik, DE): 6 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
  • ✓ All reachable over IPv6 #13
    Every nameserver has an IPv6 address.

Nameservers

info

8 of 8 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
fzi-dc-05.fzi.de 141.21.0.11NOERROR, 16 ms, authoritativenoyes / yesrefused-
fzi-dc-05.fzi.de 2001:67c:2acc:10:141:21:0:11NOERROR, 11 ms, authoritativenoyes / yesrefused-
fzi-dc-06.fzi.de 141.21.0.12NOERROR, 17 ms, authoritativenoyes / yesrefused-
fzi-dc-06.fzi.de 2001:67c:2acc:10:141:21:0:12NOERROR, 11 ms, authoritativenoyes / yesrefused-
fzi-dc-07.fzi.de 141.21.0.13NOERROR, 17 ms, authoritativenoyes / yesrefused-
fzi-dc-07.fzi.de 2001:67c:2acc:10:141:21:0:13NOERROR, 12 ms, authoritativenoyes / yesrefused-
nsb0.schlundtech.de 185.132.35.227NOERROR, 3 ms, authoritativenoyes / yesrefusedServed by PowerDNS - https://www.powerdns.com/
nsb0.schlundtech.de 2607:f1c0:fe:53:185:132:35:227NOERROR, 7 ms, authoritativenoyes / yesrefusedServed by PowerDNS - https://www.powerdns.com/

Checks

  • ✓ All respond #14
    All 8 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: nsb0.schlundtech.de: "Served by PowerDNS - https://www.powerdns.com/".
    #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 2015134451 · primary fzi-dc-06.fzi.de

Found

Primary (MNAME)
fzi-dc-06.fzi.de
Contact (RNAME)
hostmaster.fzi.de
Serial
2015134451
Refresh / retry
10800 s / 1800 s
Expire
1209600 s
Negative TTL
3600 s

Serial per nameserver

NameserverSerial
fzi-dc-05.fzi.de (141.21.0.11)2015134451
fzi-dc-05.fzi.de (2001:67c:2acc:10:141:21:0:11)2015134451
fzi-dc-06.fzi.de (141.21.0.12)2015134451
fzi-dc-06.fzi.de (2001:67c:2acc:10:141:21:0:12)2015134451
fzi-dc-07.fzi.de (141.21.0.13)2015134451
fzi-dc-07.fzi.de (2001:67c:2acc:10:141:21:0:13)2015134451
nsb0.schlundtech.de (185.132.35.227)2015134451
nsb0.schlundtech.de (2607:f1c0:fe:53:185:132:35:227)2015134451

Checks

  • ✓ Serial 2015134451 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 3h, retry 30m, expire 14d, negative TTL 1h.
  • ✓ Primary is a public nameserver #24
    The primary nameserver fzi-dc-06.fzi.de is one of the listed nameservers.
  • ✓ Contact hostmaster@fzi.de #25
    The SOA RNAME hostmaster.fzi.de means hostmaster@fzi.de.
  • ✓ Timestamp serial #26
    The serial 2015134451 is a Unix timestamp (2033-11-09 07:34 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

info

21 records at the apex

Found

Read from
141.21.0.11:53
TypeValueTTL
SOAfzi-dc-06.fzi.de. hostmaster.fzi.de. 2015134451 10800 1800 1209600 36003600
NSfzi-dc-07.fzi.de.3600
NSnsb0.schlundtech.de.43200
NSfzi-dc-05.fzi.de.3600
NSfzi-dc-06.fzi.de.3600
A141.21.0.123600
A141.21.0.13600
A141.21.0.113600
AAAA2001:67c:2acc:10:141:21:0:123600
AAAA2001:67c:2acc:10:141:21:0:13600
AAAA2001:67c:2acc:10:141:21:0:113600
MX10 fzi-mail-in-01.fzi.de.3600
MX50 fzi-mail-in-02.fzi.de.3600
TXT"MS=763AA842D08DE7042FBF886A00AF70080905CCBE"3600
TXT"openai-domain-verification=dv-ABhzqdQutjj3nwzYTHmSPoYE"3600
TXT"apple-domain-verification=qto0rDt8aOf5YExZ"3600
TXT"HARICA-wf2GwMzxpcGvurQdyUH"3600
TXT"anthropic-domain-verification-5t4w82=6OLJEaHFb1JUmG7S0hIFdXS3w"3600
TXT"ZOOM_verify_HeekmtpmSISwv6WSB3adbQ"3600
TXT"v=spf1 ip4:141.21.17.46 ip4:141.21.17.47 ip6:2001:67c:2acc:8:141:21:17:46 ip6:2001:67c:2acc:8:141:21:17:47 ip4:141.21.8.137 ip6:2001:67c:2acc:5:141:21:8:137 ip4:141.21.8.250 ip4:141.21.8.251 ip4:141.21.8.252 include:spf.protection.outlook.com -all"3600
TXT"google-site-verification=QuCAZOKIKKrqegNqJLwGZ9chipWDlLA6ejkM0x3GjX8"3600

Checks

  • ✓ TTLs within range #32
    TTLs: A 1h, AAAA 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.
  • 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