Domain report: hhu.de

Registration

info

.de country-code

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.
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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

info

dns-1.dfn.de, dns-2.dfn.de, dns-3.dfn.de, selene.rz.uni-duesseldorf.de, sirene.rz.uni-duesseldorf.de

Parent zone: de
Delegation from: a.nic.de (194.0.0.53)
NS at the parent: dns-1.dfn.de, dns-2.dfn.de, dns-3.dfn.de, selene.rz.uni-duesseldorf.de, sirene.rz.uni-duesseldorf.de
NS in the zone: dns-1.dfn.de, dns-2.dfn.de, dns-3.dfn.de, selene.rz.uni-duesseldorf.de, sirene.rz.uni-duesseldorf.de

Nameserver	Addresses	Network (AS)	Glue
dns-1.dfn.de	193.174.75.50 2001:638:d:b101::1	AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE	-
dns-2.dfn.de	193.174.75.54 2001:638:d:b102::1	AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE	-
dns-3.dfn.de	193.174.75.58 2001:638:d:b103::1	AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE	-
selene.rz.uni-duesseldorf.de	134.99.128.5	AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE	134.99.128.5
sirene.rz.uni-duesseldorf.de	134.99.128.2	AS680 DFN - Verein zur Foerderung eines Deutschen Forschungsnetzes e.V., DE	134.99.128.2

✓ 5 nameservers #6

Delegated to dns-1.dfn.de, dns-2.dfn.de, dns-3.dfn.de, selene.rz.uni-duesseldorf.de, sirene.rz.uni-duesseldorf.de.
✓ Parent and zone agree #7

The parent delegation and the zone's NS records list the same nameservers.
✓ No glue needed #8

All nameservers are outside the zone, so no glue records are needed.
✓ All names resolve #9

Every nameserver name has an address and is not an alias.
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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
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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
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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
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Partly IPv6

These nameservers have no IPv6 address: selene.rz.uni-duesseldorf.de, sirene.rz.uni-duesseldorf.de.

#13

fail

6 of 8 addresses answer authoritatively

Nameserver	Answer	Recursion	TCP / EDNS	AXFR	Version
dns-1.dfn.de 193.174.75.50	NOERROR, 12 ms, authoritative	no	yes / yes	refused	0
dns-1.dfn.de 2001:638:d:b101::1	NOERROR, 14 ms, authoritative	no	yes / yes	refused	0
dns-2.dfn.de 193.174.75.54	NOERROR, 7 ms, authoritative	no	yes / yes	refused	0
dns-2.dfn.de 2001:638:d:b102::1	NOERROR, 7 ms, authoritative	no	yes / yes	refused	0
dns-3.dfn.de 193.174.75.58	NOERROR, 8 ms, authoritative	no	yes / yes	refused	0
dns-3.dfn.de 2001:638:d:b103::1	NOERROR, 8 ms, authoritative	no	yes / yes	refused	0
selene.rz.uni-duesseldorf.de 134.99.128.5	no response	no	no / no	-	-
sirene.rz.uni-duesseldorf.de 134.99.128.2	no response	no	no / no	-	-

✗

Nameservers not responding

These addresses did not answer, so resolvers waste time on timeouts: selene.rz.uni-duesseldorf.de (134.99.128.5): read udp 46.225.38.91:40571->134.99.128.5:53: i/o timeout; sirene.rz.uni-duesseldorf.de (134.99.128.2): read udp 46.225.38.91:48893->134.99.128.2:53: i/o timeout.

#14
✓ 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: dns-1.dfn.de: "0"; dns-2.dfn.de: "0"; dns-3.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.

pass

serial 2026101902 · primary sirene.rz.uni-duesseldorf.de

✓ Serial 2026101902 everywhere #22

All nameservers serve the same version of the zone.
✓ Timers within recommendations #23

SOA refresh 1h, retry 10m, expire 21d, negative TTL 1h.
✓ Primary is a public nameserver #24

The primary nameserver sirene.rz.uni-duesseldorf.de is one of the listed nameservers.
✓ Contact hostmaster@uni-duesseldorf.de #25

The SOA RNAME hostmaster.uni-duesseldorf.de means hostmaster@uni-duesseldorf.de.
✓ Date-based serial #26

The serial 2026101902 follows the YYYYMMDDnn convention (2026-10-19).

warn

Not signed

warn

25 records at the apex

Type	Value	TTL
SOA	sirene.rz.uni-duesseldorf.de. hostmaster.uni-duesseldorf.de. 2026101902 3600 600 1814400 3600	3600
NS	selene.rz.uni-duesseldorf.de.	3600
NS	sirene.rz.uni-duesseldorf.de.	3600
NS	dns-2.dfn.de.	3600
NS	dns-3.dfn.de.	3600
NS	dns-1.dfn.de.	3600
A	134.99.128.238	3600
MX	10 a2881.mx.srv.dfn.de.	60
MX	10 b2881.mx.srv.dfn.de.	60
MX	10 c2881.mx.srv.dfn.de.	60
TXT	"google-site-verification=kiygt8zU6VCAudun5LjKaoOEIJNgoM2yBWjSksiXaIw"	3600
TXT	"T222-U324-V252"	3600
TXT	"security_contact=cert@hhu.de"	3600
TXT	"HARICA-b01FuDqexohoPakaPN0"	3600
TXT	"adobe-idp-site-verification=18ec973e322894c7c0c11b75d7434eb7c4a5b8d2f164b30a6d47f928c7b5f811"	3600
TXT	"b7363772c1b9953bc35b74b12e12c69c"	3600
TXT	"v=spf1 ip4:134.99.18.0/24 ip4:134.99.128.0/24 ip4:134.99.108.0/27 ip4:134.99.108.128/27 include:spf.qb-feedback.com include:_spf.o288.mx.srv.dfn.de -all"	3600
TXT	"cisco-ci-domain-verification=4a60e9dddacd024a7029731869b6259bfb32e550f5004eb699afadf7d558cbf"	3600
TXT	"security_policy=https://www.hhu.de/it-sicherheit"	3600
CAA	0 issue "pki.dfn.de"	3600
CAA	0 issuewild "harica.gr"	3600
CAA	0 issue "telesec.de"	3600
CAA	0 issue "harica.gr"	3600
CAA	0 iodef "mailto:cert@hhu.de"	3600
CAA	0 issue "sectigo.com"	3600

!

Very low TTLs

These records have a TTL below 5m, causing extra queries and slower lookups: MX (1m). Low TTLs are useful just before a planned change. The NS TTL at the parent is 1d and in the zone 1h; resolvers may use either.

#32
✓ 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, harica.gr, telesec.de, sectigo.com.