Domain report: hotelschool.nl

Registration

info

.nl country-code

Found

TLD: .nl (country-code)
ICANN policies apply: no

Lookup error: https://rdap.sidn.nl/domain/hotelschool.nl returned HTTP 429

Checks

i

.nl 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

.nl is delegated in the root zone and DNSSEC-signed.
i

Could not be checked

The RDAP lookup failed, so this could not be checked: https://rdap.sidn.nl/domain/hotelschool.nl returned HTTP 429

#3

Delegation

info

ns1.hdh.nl, ns1.surfnet.nl, ns1.zurich.surf.net

Found

Parent zone: nl
Delegation from: ns1.dns.nl (194.0.28.53)
NS at the parent: ns1.hdh.nl, ns1.surfnet.nl, ns1.zurich.surf.net
NS in the zone: ns1.hdh.nl, ns1.surfnet.nl, ns1.zurich.surf.net

Nameserver	Addresses	Network (AS)	Glue
ns1.hdh.nl	52.136.200.63	AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation, US	52.136.200.63
ns1.surfnet.nl	192.87.106.101 2001:610:1:800a:192:87:106:101	AS1103 SURFNET-NL - SURF B.V., NL AS1103 SURFNET-NL - SURF B.V., NL	192.87.106.101 2001:610:1:800a:192:87:106:101
ns1.zurich.surf.net	195.176.255.9 2001:620:0:9::1103	AS559 Switch - SWITCH, CH AS559 Switch - SWITCH, CH	-

Checks

✓ 3 nameservers #6

Delegated to ns1.hdh.nl, ns1.surfnet.nl, ns1.zurich.surf.net.
✓ 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.
✓ Nameservers in different networks #10

The nameservers are spread over 3 IPv4 /24s and 2 IPv6 /48s.
✓ 3 autonomous systems #11

The nameservers are spread over: AS1103 (SURFNET-NL - SURF B.V., NL): 2 addresses; AS559 (Switch - SWITCH, CH): 2 addresses; AS8075 (MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation, US): 1 address.
✓ Nameserver names under 2 TLDs #12

Nameserver names use the TLDs .net, .nl.
i

Partly IPv6

These nameservers have no IPv6 address: ns1.hdh.nl.

#13

Nameservers

fail

5 of 5 addresses answer authoritatively

Found

Nameserver	Answer	Recursion	TCP / EDNS	AXFR	Version
ns1.hdh.nl 52.136.200.63	NOERROR, 14 ms, authoritative	no	yes / yes	ALLOWED (596 records)	9.11.5-P4-5.1+deb10u11-Debian
ns1.surfnet.nl 192.87.106.101	NOERROR, 9 ms, authoritative	no	yes / yes	refused	This is a SURFnet nameserver - dns-beheer@surfnet.nl
ns1.surfnet.nl 2001:610:1:800a:192:87:106:101	NOERROR, 9 ms, authoritative	no	yes / yes	refused	This is a SURFnet nameserver - dns-beheer@surfnet.nl
ns1.zurich.surf.net 195.176.255.9	NOERROR, 9 ms, authoritative	no	yes / yes	refused	This is a SURFnet nameserver - dns-beheer@surf.nl
ns1.zurich.surf.net 2001:620:0:9::1103	NOERROR, 10 ms, authoritative	no	yes / yes	refused	This is a SURFnet nameserver - dns-beheer@surf.nl

Checks

✓ All respond #14

All 5 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: ns1.hdh.nl: "9.11.5-P4-5.1+deb10u11-Debian". Hide or replace the version string.

#17
✗

Zone transfer allowed

These nameservers send the complete zone to anyone who asks (AXFR), exposing all host names: ns1.hdh.nl (52.136.200.63): 596 records. Restrict zone transfers to your secondary servers.

#18
✓ 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 2026072120 · primary ns1.hdh.nl

Found

Primary (MNAME): ns1.hdh.nl
Contact (RNAME): hostmaster.hdh.nl
Serial: 2026072120
Refresh / retry: 14400 s / 3600 s
Expire: 604800 s
Negative TTL: 86400 s

Serial per nameserver

Nameserver	Serial
ns1.hdh.nl (52.136.200.63)	2026072120
ns1.surfnet.nl (192.87.106.101)	2026072120
ns1.surfnet.nl (2001:610:1:800a:192:87:106:101)	2026072120
ns1.zurich.surf.net (195.176.255.9)	2026072120
ns1.zurich.surf.net (2001:620:0:9::1103)	2026072120

Checks

✓ Serial 2026072120 everywhere #22

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

SOA refresh 4h, retry 1h, expire 7d, negative TTL 1d.
✓ Primary is a public nameserver #24

The primary nameserver ns1.hdh.nl is one of the listed nameservers.
✓ Contact hostmaster@hdh.nl #25

The SOA RNAME hostmaster.hdh.nl means hostmaster@hdh.nl.
✓ Date-based serial #26

The serial 2026072120 follows the YYYYMMDDnn convention (2026-07-21).

DNSSEC

warn

Signed, DS published at parent

Found

Validated by resolver: yes
Denial of existence: NSEC3
NSEC3: 10 iterations, 0-byte salt
Signatures valid until: 11 November 2026

DS at the parent

Key tag	Algorithm	Digest	Matches a key
18227	RSASHA256 (8)	SHA256 417F39550D45E1C7…	yes

DNSKEY in the zone

Key tag	Role	Algorithm
37971	ZSK (256)	RSASHA256 (8)
18227	KSK (257)	RSASHA256 (8)

Checks

✓ Signed and validated #27

The zone is signed, the parent publishes a DS record, and the resolver validates the answers.
✓ DS matches a key #28

The DS record at the parent matches a key in the zone: key tag 18227 (SHA256).
✓ Modern algorithms #29

Key algorithms: RSASHA256 (8).
✓ Signatures valid until 2026-11-11 #30

The earliest DNSKEY/SOA signature expires at 2026-11-11 03:59 UTC.
!

NSEC3 with extra iterations or salt

NSEC3 uses 10 iterations and a 0-byte salt. RFC 9276 recommends 0 iterations and no salt: extra iterations cost resolvers CPU and add no real protection, and some validators treat high counts as insecure.

#31

Records

pass

17 records at the apex

Found

Read from: 52.136.200.63:53

Type	Value	TTL
SOA	ns1.hdh.nl. hostmaster.hdh.nl. 2026072120 14400 3600 604800 86400	46800
NS	ns1.hdh.nl.	1800
NS	ns1.zurich.surf.net.	1800
NS	ns1.surfnet.nl.	1800
A	4.175.39.140	300
MX	0 hotelschool-nl.mail.protection.outlook.com.	3600
TXT	"hpe-greenlake-domain-verification=7150534c6338636f4c6d4847306f5779714b744a4c7a466b4c65416141676465"	2600
TXT	"d365mktkey=3qaXE9xxKxW7HxRB4WSQrJBQNXeGB0c9vDgxOyxqxzQx"	2600
TXT	"v=spf1 a mx a:mx01.hotelschool.nl ip4:83.149.98.72 ip4:13.93.30.160 ip4:167.89.85.140 ip4:163.172.178.119 ip4:50.31.44.73 ip4:138.68.90.113 ip4:52.236.141.67 include:spf1.hotelschool.nl include:spf.protection.outlook.com include:spf.interconnect.nl " "include:spf.otys.nl include:_spf.salesforce.com -all"	2600
TXT	"cisco-ci-domain-verification=1a8005d60c94e19c452ac68c07c5be1696b97cf50b0456f971961af6d23df67f"	2600
TXT	"HARICA-L5r4i7ALog0oCNZshH3"	2600
TXT	"d365mktkey=Z5j8yyOcbBwTj2XR1IfyVsDicE6zzaMZWvsqMdzbqeQx"	2600
TXT	"teamtailor=bf61c342073c7ef9d109633eb8c5e5a6"	2600
TXT	"fff9eea32a864e21a41d498286f25e20"	2600
CAA	0 issue "certainly.com"	2600
CAA	0 issue "letsencrypt.org"	2600
CAA	0 issue "harica.gr"	2600

Checks

✓ TTLs within range #32

TTLs: A 5m, MX 1h, NS 30m. The NS TTL at the parent is 1h and in the zone 30m; 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.
✓ CAA restricts issuance #35

Certificates may be issued by: certainly.com, letsencrypt.org, harica.gr.