diw.de

Checked 21 October 2026, 22:14 UTC · via 8.8.8.8
!Passed with warnings
22 passed 1 warning 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

info

deneb.dfn.de, dns1.diw.de, dns2.diw.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
deneb.dfn.de, dns1.diw.de, dns2.diw.de
NS in the zone
deneb.dfn.de, dns1.diw.de, dns2.diw.de
NameserverAddressesNetwork (AS)Glue
deneb.dfn.de192.76.176.9 2001:638:800:1::9AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE-
dns1.diw.de193.174.141.138AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE193.174.141.138
dns2.diw.de193.174.141.139AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE193.174.141.139

Checks

  • ✓ 3 nameservers #6
    Delegated to deneb.dfn.de, dns1.diw.de, dns2.diw.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: dns1.diw.de, dns2.diw.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 1 IPv6 /48.
  • 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): 4 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: dns1.diw.de, dns2.diw.de.
    #13

Nameservers

info

4 of 4 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
deneb.dfn.de 192.76.176.9NOERROR, 14 ms, authoritativenoyes / yesrefused0
deneb.dfn.de 2001:638:800:1::9NOERROR, 14 ms, authoritativenoyes / yesrefused0
dns1.diw.de 193.174.141.138NOERROR, 13 ms, authoritativenoyes / yesrefused-
dns2.diw.de 193.174.141.139NOERROR, 18 ms, authoritativenoyes / yesrefused-

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.
  • i
    Identifying string disclosed
    These nameservers answer version queries with a string that is not a version number: deneb.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

pass

serial 2026101601 · primary dns1.diw.de

Found

Primary (MNAME)
dns1.diw.de
Contact (RNAME)
server-admins.diw.de
Serial
2026101601
Refresh / retry
21600 s / 7200 s
Expire
1800000 s
Negative TTL
86400 s

Serial per nameserver

NameserverSerial
deneb.dfn.de (192.76.176.9)2026101601
deneb.dfn.de (2001:638:800:1::9)2026101601
dns1.diw.de (193.174.141.138)2026101601
dns2.diw.de (193.174.141.139)2026101601

Checks

  • ✓ Serial 2026101601 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 6h, retry 2h, expire 500h, negative TTL 1d.
  • ✓ Primary is a public nameserver #24
    The primary nameserver dns1.diw.de is one of the listed nameservers.
  • ✓ Contact server-admins@diw.de #25
    The SOA RNAME server-admins.diw.de means server-admins@diw.de.
  • ✓ Date-based serial #26
    The serial 2026101601 follows the YYYYMMDDnn convention (2026-10-16).

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

14 records at the apex

Found

Read from
192.76.176.9:53
TypeValueTTL
SOAdns1.diw.de. server-admins.diw.de. 2026101601 21600 7200 1800000 8640086400
NSdns1.diw.de.86400
NSdns2.diw.de.86400
NSdeneb.dfn.de.86400
A195.90.222.1443600
MX0 diw-de.mail.protection.outlook.com.86400
TXT"linkedin-site-verification=f52e6b05-e986-4f0a-810f-a7177f3f7e4a"86400
TXT"HARICA-SkEWMtcCtdd62j5bRWY"86400
TXT"apple-domain-verification=4V8rGV5u89tZuXjs"86400
TXT"v=spf1 mx include:spf.protection.outlook.com ip4:193.174.142.20 ip4:193.174.141.161 ip4:193.174.141.162 " " ip4:193.174.141.120 ip4:193.174.141.121 ip4:193.174.141.122 ip4:193.174.142.69 ip4:193.174.141.140 -all"86400
CAA0 issue "pki.dfn.de"86400
CAA0 issue "sectigo.com"86400
CAA0 iodef "mailto:hostmaster@diw.de"86400
CAA0 issue "harica.gr"86400

Checks

  • ✓ TTLs within range #32
    TTLs: A 1h, MX 1d, NS 1d.
  • ✓ 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: pki.dfn.de, sectigo.com, harica.gr.