Domain report: cwi.nl

Registration

info

.nl country-code

Found

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

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

#3

Delegation

info

dwalin.nikhef.nl, ns1.cwi.nl, ns1.zurich.surf.net, ns2.cwi.nl

Found

Parent zone: nl
Delegation from: ns1.dns.nl (194.0.28.53)
NS at the parent: dwalin.nikhef.nl, ns1.cwi.nl, ns1.zurich.surf.net, ns2.cwi.nl
NS in the zone: dwalin.nikhef.nl, ns1.cwi.nl, ns1.zurich.surf.net, ns2.cwi.nl

Nameserver	Addresses	Network (AS)	Glue
dwalin.nikhef.nl	192.16.199.17 2001:610:120:1000::199:17	AS1104 Nikhef - Stichting Nederlandse Wetenschappelijk Onderzoek Instituten, NL AS1103 SURFNET-NL - SURF B.V., NL	192.16.199.17 2001:610:120:1000::199:17
ns1.cwi.nl	192.16.191.8	AS1888 CWI-NL - CWI-NL, NL	192.16.191.8
ns1.zurich.surf.net	195.176.255.9 2001:620:0:9::1103	AS559 Switch - SWITCH, CH AS559 Switch - SWITCH, CH	-
ns2.cwi.nl	192.16.191.36	AS1888 CWI-NL - CWI-NL, NL	192.16.191.36

Checks

✓ 4 nameservers #6

Delegated to dwalin.nikhef.nl, ns1.cwi.nl, ns1.zurich.surf.net, ns2.cwi.nl.
✓ 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: ns1.cwi.nl, ns2.cwi.nl.
✓ 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.
✓ 4 autonomous systems #11

The nameservers are spread over: AS1103 (SURFNET-NL - SURF B.V., NL): 1 address; AS1104 (Nikhef - Stichting Nederlandse Wetenschappelijk Onderzoek Instituten, NL): 1 address; AS1888 (CWI-NL - CWI-NL, NL): 2 addresses; AS559 (Switch - SWITCH, CH): 2 addresses.
✓ Nameserver names under 2 TLDs #12

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

Partly IPv6

These nameservers have no IPv6 address: ns1.cwi.nl, ns2.cwi.nl.

#13

Nameservers

info

6 of 6 addresses answer authoritatively

Found

Nameserver	Answer	Recursion	TCP / EDNS	AXFR	Version
dwalin.nikhef.nl 192.16.199.17	NOERROR, 9 ms, authoritative	no	yes / yes	refused	-
dwalin.nikhef.nl 2001:610:120:1000::199:17	NOERROR, 10 ms, authoritative	no	yes / yes	refused	-
ns1.cwi.nl 192.16.191.8	NOERROR, 9 ms, authoritative	no	yes / yes	refused	not your business
ns1.zurich.surf.net 195.176.255.9	NOERROR, 10 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, 9 ms, authoritative	no	yes / yes	refused	This is a SURFnet nameserver - dns-beheer@surf.nl
ns2.cwi.nl 192.16.191.36	NOERROR, 10 ms, authoritative	no	yes / yes	refused	not your business

Checks

✓ All respond #14

All 6 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: ns1.cwi.nl: "not your business"; ns1.zurich.surf.net: "This is a SURFnet nameserver - dns-beheer@surf.nl"; ns2.cwi.nl: "not your business".

#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 2026101603 · primary ns1.cwi.nl

Found

Primary (MNAME): ns1.cwi.nl
Contact (RNAME): hostmaster.cwi.nl
Serial: 2026101603
Refresh / retry: 28800 s / 7200 s
Expire: 604800 s
Negative TTL: 43200 s

Serial per nameserver

Nameserver	Serial
dwalin.nikhef.nl (192.16.199.17)	2026101603
dwalin.nikhef.nl (2001:610:120:1000::199:17)	2026101603
ns1.cwi.nl (192.16.191.8)	2026101603
ns1.zurich.surf.net (195.176.255.9)	2026101603
ns1.zurich.surf.net (2001:620:0:9::1103)	2026101603
ns2.cwi.nl (192.16.191.36)	2026101603

Checks

✓ Serial 2026101603 everywhere #22

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

SOA refresh 8h, retry 2h, expire 7d, negative TTL 12h.
✓ Primary is a public nameserver #24

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

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

The serial 2026101603 follows the YYYYMMDDnn convention (2026-10-16).

DNSSEC

warn

Signed, DS published at parent

Found

Validated by resolver: yes
Denial of existence: NSEC3
NSEC3: 0 iterations, 8-byte salt
Signatures valid until: 15 December 2026

DS at the parent

Key tag	Algorithm	Digest	Matches a key
56785	RSASHA256 (8)	SHA256 14C2AF77C4F5C1A4…	yes

DNSKEY in the zone

Key tag	Role	Algorithm
56785	KSK (257)	RSASHA256 (8)
32073	ZSK (256)	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 56785 (SHA256).
✓ Modern algorithms #29

Key algorithms: RSASHA256 (8).
✓ Signatures valid until 2026-12-15 #30

The earliest DNSKEY/SOA signature expires at 2026-12-15 08:16 UTC.
!

NSEC3 with extra iterations or salt

NSEC3 uses 0 iterations and a 8-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

info

17 records at the apex

Found

Read from: 192.16.199.17:53

Type	Value	TTL
SOA	ns1.cwi.nl. hostmaster.cwi.nl. 2026101603 28800 7200 604800 43200	86400
NS	dwalin.nikhef.nl.	86400
NS	ns1.cwi.nl.	86400
NS	ns1.zurich.surf.net.	86400
NS	ns2.cwi.nl.	86400
A	192.16.191.48	86400
MX	10 mx.soverin.net.	300
TXT	"CWI (Centrum Wiskunde & Informatica)=pnqgTeOiurzbz4yD"	86400
TXT	"adobe-idp-site-verification=a8667c98581a66df82f18dd9b4ec9ad04d2b0214fda298afa04b69ae89b16b4d"	86400
TXT	"v=spf1 ip4:192.16.191.0/27 ip4:192.174.88.179 ip4:192.174.88.180 ip4:13.58.74.171 include:_spf.surfmailfilter.nl include:projects5.greenlightsolutions.nl include:spf.protection.outlook.com ~all"	86400
TXT	"MS=ms63043750"	86400
TXT	"HARICA-SnDN4Irx82qOUXNni8S"	86400
TXT	"Centrum Wiskunde & Informatica"	86400
TXT	"ZOOM_verify_-TwabqfPQI2RrsWzDjTwfQ"	86400
TXT	"ZOOM_verify_QtFtKLPNUTBlqUfH6kXTNZ"	86400
TXT	"apple-domain-verification=vKvt2VfbB2WZUhzQ"	86400
TXT	"Science Park 123, 1098 XG Amsterdam, Netherlands"	86400

Checks

✓ TTLs within range #32

TTLs: A 1d, MX 5m, NS 1d. The NS TTL at the parent is 1h and in the zone 1d; 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