rwi-essen.de

Checked 22 October 2026, 00:01 UTC · via 8.8.8.8
!Passed with warnings
20 passed 2 warnings 0 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

deneb.dfn.de, sun01.rwi-essen.de

Found

Parent zone
de
Delegation from
a.nic.de (194.0.0.53)
NS at the parent
deneb.dfn.de, sun01.rwi-essen.de
NS in the zone
deneb.dfn.de, sun01.rwi-essen.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-
sun01.rwi-essen.de194.94.247.1AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE194.94.247.1

Checks

  • i
    2 nameservers
    Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: deneb.dfn.de, sun01.rwi-essen.de.
    #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: sun01.rwi-essen.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): 3 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: sun01.rwi-essen.de.
    #13

Nameservers

warn

3 of 3 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
sun01.rwi-essen.de 194.94.247.1NOERROR, 8 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.24.04.8-Ubuntu

Checks

  • ✓ All respond #14
    All 3 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: sun01.rwi-essen.de: "9.18.39-0ubuntu0.24.04.8-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 2026070114 · primary sun01.rwi-essen.de

Found

Primary (MNAME)
sun01.rwi-essen.de
Contact (RNAME)
hostmaster.rwi-essen.de
Serial
2026070114
Refresh / retry
14400 s / 3600 s
Expire
1209600 s
Negative TTL
900 s

Serial per nameserver

NameserverSerial
deneb.dfn.de (192.76.176.9)2026070114
deneb.dfn.de (2001:638:800:1::9)2026070114
sun01.rwi-essen.de (194.94.247.1)2026070114

Checks

  • ✓ Serial 2026070114 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 4h, retry 1h, expire 14d, negative TTL 15m.
  • ✓ Primary is a public nameserver #24
    The primary nameserver sun01.rwi-essen.de is one of the listed nameservers.
  • ✓ Contact hostmaster@rwi-essen.de #25
    The SOA RNAME hostmaster.rwi-essen.de means hostmaster@rwi-essen.de.
  • ✓ Date-based serial #26
    The serial 2026070114 follows the YYYYMMDDnn convention (2026-07-01).

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

10 records at the apex

Found

Read from
192.76.176.9:53
TypeValueTTL
SOAsun01.rwi-essen.de. hostmaster.rwi-essen.de. 2026070114 14400 3600 1209600 900900
NSdeneb.dfn.de.900
NSsun01.rwi-essen.de.900
A194.94.247.252900
MX10 rwiessen-de0i.mail.protection.outlook.com.900
TXT"sophos-domain-verification=fd2fc777a34af8217236d6745f092fdd1d54f60f"900
TXT"MS=ms71593155"900
TXT"v=spf1 mx ip4:194.94.247.58 ip4:194.94.247.56 include:spf.protection.outlook.com include:_spf.prod.hydra.sophos.com include:spf.crsend.com ip4:85.13.152.215 ip4:194.94.247.250 -all"900
TXT"sophos-domain-verification=ee1c12c077e531c76e103beed89930a8d1fd5c8c0f31a9e16005f129e53b0fde"900
TXT"/VsCm9a7Zh27NUu9QNMX3KWwbtOcrZ9Xs6DWKEVC3E3ztux4lp/WSd0PtredAOknOZBx3kq5/nPi5QY8W43P/g=="900

Checks

  • ✓ TTLs within range #32
    TTLs: A 15m, MX 15m, NS 15m. The NS TTL at the parent is 1d and in the zone 15m; 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