schule.de

Checked 22 October 2026, 00:02 UTC · via 8.8.8.8
!Passed with warnings
22 passed 2 warnings 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

arbi.informatik.uni-oldenburg.de, dns-1.schule.de, dns-3.dfn.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
arbi.informatik.uni-oldenburg.de, dns-1.schule.de, dns-3.dfn.de
NS in the zone
arbi.informatik.uni-oldenburg.de, dns-1.schule.de, dns-3.dfn.de
NameserverAddressesNetwork (AS)Glue
arbi.informatik.uni-oldenburg.de134.106.1.7AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE134.106.1.7
dns-1.schule.de80.239.207.166AS1299 TWELVE99 - Arelion Sweden AB, SE80.239.207.166
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 arbi.informatik.uni-oldenburg.de, dns-1.schule.de, dns-3.dfn.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: dns-1.schule.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.
  • ✓ 2 autonomous systems #11
    The nameservers are spread over: AS1299 (TWELVE99 - Arelion Sweden AB, SE): 1 address; AS680 (DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE): 3 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: arbi.informatik.uni-oldenburg.de, dns-1.schule.de.
    #13

Nameservers

warn

4 of 4 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
arbi.informatik.uni-oldenburg.de 134.106.1.7NOERROR, 21 ms, authoritativenoyes / yesrefused9.18.21
dns-1.schule.de 80.239.207.166NOERROR, 21 ms, authoritativenoyes / yesrefusednone
dns-3.dfn.de 193.174.75.58NOERROR, 8 ms, authoritativenoyes / yesrefused0
dns-3.dfn.de 2001:638:d:b103::1NOERROR, 11 ms, authoritativenoyes / yesrefused0

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.
  • !
    Software version disclosed
    These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: arbi.informatik.uni-oldenburg.de: "9.18.21". 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

pass

serial 2026101703 · primary dns-1.schule.de

Found

Primary (MNAME)
dns-1.schule.de
Contact (RNAME)
ballier.schule.de
Serial
2026101703
Refresh / retry
10800 s / 3600 s
Expire
1209600 s
Negative TTL
10800 s

Serial per nameserver

NameserverSerial
arbi.informatik.uni-oldenburg.de (134.106.1.7)2026101703
dns-1.schule.de (80.239.207.166)2026101703
dns-3.dfn.de (193.174.75.58)2026101703
dns-3.dfn.de (2001:638:d:b103::1)2026101703

Checks

  • ✓ Serial 2026101703 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 3h, retry 1h, expire 14d, negative TTL 3h.
  • ✓ Primary is a public nameserver #24
    The primary nameserver dns-1.schule.de is one of the listed nameservers.
  • ✓ Contact ballier@schule.de #25
    The SOA RNAME ballier.schule.de means ballier@schule.de.
  • ✓ Date-based serial #26
    The serial 2026101703 follows the YYYYMMDDnn convention (2026-10-17).

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

9 records at the apex

Found

Read from
134.106.1.7:53
TypeValueTTL
SOAdns-1.schule.de. ballier.schule.de. 2026101703 10800 3600 1209600 108003600
NSdns-3.dfn.de.3600
NSarbi.informatik.uni-oldenburg.de.3600
NSdns-1.schule.de.3600
A80.239.207.1663600
MX0 mail.schule.de.3600
TXT"MS=ms36740436"3600
TXT"apple-domain-verification=P8F7htQPtFb9Bh0S"3600
TXT"v=spf1 ip4:80.239.207.166 ip4:80.239.175.166 ip4:194.164.202.117 ip4:85.214.45.105 ~all"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.
  • 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