dhm.de

Checked 21 October 2026, 22:14 UTC · via 8.8.8.8
✗Problems found
18 passed 3 warnings 1 failed 7 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

dns-2.dfn.de, dns-3.dfn.de, srvns01.dhm.de, srvns02.dhm.de, srvns03.dhm.de, srvns04.dhm.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
dns-2.dfn.de, dns-3.dfn.de, srvns01.dhm.de, srvns02.dhm.de, srvns03.dhm.de, srvns04.dhm.de
NS in the zone
dns-2.dfn.de, dns-3.dfn.de, srvns01.dhm.de, srvns02.dhm.de, srvns03.dhm.de, srvns04.dhm.de
NameserverAddressesNetwork (AS)Glue
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-
srvns01.dhm.de194.94.40.81AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE194.94.40.81
srvns02.dhm.de194.94.40.82AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE194.94.40.82
srvns03.dhm.de194.94.40.83AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE194.94.40.83
srvns04.dhm.de194.94.40.84AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE194.94.40.84

Checks

  • ✓ 6 nameservers #6
    Delegated to dns-2.dfn.de, dns-3.dfn.de, srvns01.dhm.de, srvns02.dhm.de, srvns03.dhm.de, srvns04.dhm.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: srvns01.dhm.de, srvns02.dhm.de, srvns03.dhm.de, srvns04.dhm.de.
  • ✓ All names resolve #9
    Every nameserver name has an address and is not an alias.
  • i
    One address family in one network
    all IPv6 addresses are in 2001:638:d::/48, while the other address family is spread over several networks.
    #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): 8 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
  • i
    Partly IPv6
    These nameservers have no IPv6 address: srvns01.dhm.de, srvns02.dhm.de, srvns03.dhm.de, srvns04.dhm.de.
    #13

Nameservers

fail

8 of 8 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
dns-2.dfn.de 193.174.75.54NOERROR, 6 ms, authoritativenoyes / yesrefused0
dns-2.dfn.de 2001:638:d:b102::1NOERROR, 6 ms, authoritativenoyes / yesrefused0
dns-3.dfn.de 193.174.75.58NOERROR, 10 ms, authoritativenoyes / yesrefused0
dns-3.dfn.de 2001:638:d:b103::1NOERROR, 8 ms, authoritativenoyes / yesrefused0
srvns01.dhm.de 194.94.40.81NOERROR, 13 ms, authoritativenono / yesrefused9.16.50-Debian
srvns02.dhm.de 194.94.40.82NOERROR, 14 ms, authoritativenono / yesrefused9.16.50-Debian
srvns03.dhm.de 194.94.40.83NOERROR, 13 ms, authoritativenono / yesrefused9.16.48-Debian
srvns04.dhm.de 194.94.40.84NOERROR, 13 ms, authoritativenono / yesrefused9.20.15-1~deb13u1-Debian

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.
  • !
    Software version disclosed
    These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: srvns01.dhm.de: "9.16.50-Debian"; srvns02.dhm.de: "9.16.50-Debian"; srvns03.dhm.de: "9.16.48-Debian"; srvns04.dhm.de: "9.20.15-1~deb13u1-Debian". Hide or replace the version string.
    #17
  • ✓ Zone transfers refused #18
    No nameserver allows a zone transfer to the public.
  • ✗
    No DNS over TCP
    DNS over TCP is required (RFC 7766); without it, large answers such as DNSSEC responses fail. Not answering over TCP: srvns01.dhm.de (194.94.40.81): dial tcp 194.94.40.81:53: i/o timeout; srvns02.dhm.de (194.94.40.82): dial tcp 194.94.40.82:53: i/o timeout; srvns03.dhm.de (194.94.40.83): dial tcp 194.94.40.83:53: i/o timeout; srvns04.dhm.de (194.94.40.84): dial tcp 194.94.40.84:53: i/o timeout.
    #19
  • ✓ EDNS supported #20
    All nameservers support EDNS(0).
  • ✓ Public addresses #21
    All nameserver addresses are publicly routable.

SOA

warn

serial 2026092301 · primary srvns01.dhm.de

Found

Primary (MNAME)
srvns01.dhm.de
Contact (RNAME)
dns-admins.dhm.de
Serial
2026092301
Refresh / retry
1800 s / 7200 s
Expire
604800 s
Negative TTL
600 s

Serial per nameserver

NameserverSerial
dns-2.dfn.de (193.174.75.54)2026092301
dns-2.dfn.de (2001:638:d:b102::1)2026092301
dns-3.dfn.de (193.174.75.58)2026092301
dns-3.dfn.de (2001:638:d:b103::1)2026092301
srvns01.dhm.de (194.94.40.81)2026092301
srvns02.dhm.de (194.94.40.82)2026092301
srvns03.dhm.de (194.94.40.83)2026092301
srvns04.dhm.de (194.94.40.84)2026092301

Checks

  • ✓ Serial 2026092301 everywhere #22
    All nameservers serve the same version of the zone.
  • !
    Unusual SOA timers
    retry 2h should be shorter than refresh 30m. Current values: refresh 30m, retry 2h, expire 7d, negative TTL 10m.
    #23
  • ✓ Primary is a public nameserver #24
    The primary nameserver srvns01.dhm.de is one of the listed nameservers.
  • ✓ Contact dns-admins@dhm.de #25
    The SOA RNAME dns-admins.dhm.de means dns-admins@dhm.de.
  • ✓ Date-based serial #26
    The serial 2026092301 follows the YYYYMMDDnn convention (2026-09-23).

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

16 records at the apex

Found

Read from
193.174.75.54:53
TypeValueTTL
SOAsrvns01.dhm.de. dns-admins.dhm.de. 2026092301 1800 7200 604800 600600
NSsrvns04.dhm.de.600
NSsrvns02.dhm.de.600
NSdns-3.dfn.de.600
NSdns-2.dfn.de.600
NSsrvns01.dhm.de.600
NSsrvns03.dhm.de.600
A194.94.40.10600
MX10 b1761.mx.srv.dfn.de.600
MX10 c1761.mx.srv.dfn.de.600
MX10 a1761.mx.srv.dfn.de.600
TXT"apple-domain-verification=sgAY5EFvUmUAcH2H"600
TXT"google-site-verification=cIW7IW9G9wg_dnM797jJXE8pEJkM1RVppcPjPpvQQ_8"600
TXT"sendinblue-code:9e6f6c9b87b71218bf71445918225ee8"600
TXT"v=spf1 include:spf.mailsupport.dfn.de ip4:194.94.40.31 ip4:194.94.40.32 ip4:194.94.40.33 ip4:194.94.40.34 ~all"600
TXT"cisco-ci-domain-verification=14c3a57e4ffedb829872176fc26c0e67563eb80bcbc34cb94d667acbf46afa22"600

Checks

  • ✓ TTLs within range #32
    TTLs: A 10m, MX 10m, NS 10m. The NS TTL at the parent is 1d and in the zone 10m; 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