kohlhammer.de

Checked 21 October 2026, 23:10 UTC · via 8.8.8.8
!Passed with warnings
21 passed 3 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

warn

gw01c.kohlhammer.de, ns1.de.colt.net

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
gw01c.kohlhammer.de, ns1.de.colt.net
NS in the zone
gw01c.kohlhammer.de, ns1.de.colt.net
NameserverAddressesNetwork (AS)Glue
gw01c.kohlhammer.de217.111.69.12AS8220 COLT - COLT Technology Services Group Limited, GB217.111.69.12
ns1.de.colt.net212.74.77.55AS8220 COLT - COLT Technology Services Group Limited, GB-

Checks

  • i
    2 nameservers
    Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: gw01c.kohlhammer.de, ns1.de.colt.net.
    #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: gw01c.kohlhammer.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 0 IPv6 /48s.
  • i
    All nameservers in one AS
    All nameserver addresses are announced by one network operator (AS8220 (COLT - COLT Technology Services Group Limited, GB): 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
  • ✓ Nameserver names under 2 TLDs #12
    Nameserver names use the TLDs .de, .net.
  • !
    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
gw01c.kohlhammer.de 217.111.69.12NOERROR, 7 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.24.04.3-Ubuntu
ns1.de.colt.net 212.74.77.55NOERROR, 15 ms, authoritativenoyes / yesrefusedColt

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: gw01c.kohlhammer.de: "9.18.39-0ubuntu0.24.04.3-Ubuntu". 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 2026102011 · primary gw01c.kohlhammer.de

Found

Primary (MNAME)
gw01c.kohlhammer.de
Contact (RNAME)
abele.kohlhammer.de
Serial
2026102011
Refresh / retry
7200 s / 600 s
Expire
2419100 s
Negative TTL
3600 s

Serial per nameserver

NameserverSerial
gw01c.kohlhammer.de (217.111.69.12)2026102011
ns1.de.colt.net (212.74.77.55)2026102011

Checks

  • ✓ Serial 2026102011 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 2h, retry 10m, expire 671h58m20s, negative TTL 1h.
  • ✓ Primary is a public nameserver #24
    The primary nameserver gw01c.kohlhammer.de is one of the listed nameservers.
  • ✓ Contact abele@kohlhammer.de #25
    The SOA RNAME abele.kohlhammer.de means abele@kohlhammer.de.
  • ✓ Date-based serial #26
    The serial 2026102011 follows the YYYYMMDDnn convention (2026-10-20).

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

8 records at the apex

Found

Read from
217.111.69.12:53
TypeValueTTL
SOAgw01c.kohlhammer.de. abele.kohlhammer.de. 2026102011 7200 600 2419100 36003600
NSns1.de.colt.net.3600
NSgw01c.kohlhammer.de.3600
A93.89.4.1843600
MX10 mailgw01.kohlhammer.de.3600
TXT"v=spf1 ip4:217.111.69.0/26 ip4:213.179.138.112 ip4:213.179.129.139 ip4:52.28.38.40 ip4:54.93.34.219 ip4:54.93.38.57 ip4:213.133.106.51 ip4:217.111.33.240/28 ip4:35.207.68.135 include:_spf.zimpel.de -all"3600
TXT"MS=ms99514044"3600
TXT"google-site-verification=rARZj5OBYggZueXbMvPwKJMGbifXupocEH-gp6tg804"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