ou.nl

Checked 21 October 2026, 21:24 UTC · via 8.8.8.8
✗Problems found
23 passed 2 warnings 1 failed 9 info

Registration

info

.nl country-code · Open Universiteit

Found

TLD
.nl (country-code)
ICANN policies apply
no
Registrar
Open Universiteit
Registered
27 November 1997
Last changed
21 April 2026
Status
active
Registry nameservers
dns.ou.nl, ns.ou.nl, ns2.ou.nl
RDAP server
https://rdap.sidn.nl/

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
    Expiry date not published
    The registry does not publish the expiry date in RDAP. Check it with your registrar.
    #3
  • i
    No transfer lock
    The domain has no transfer lock (status: active). A registrar lock protects against unauthorized transfers.
    #4
  • ✓ Registry and delegation match #5
    The nameservers registered at the registry are the ones published in DNS.

Delegation

warn

dns.ou.nl, ns.ou.nl, ns2.ou.nl

Found

Parent zone
nl
Delegation from
ns1.dns.nl (194.0.28.53)
NS at the parent
dns.ou.nl, ns.ou.nl, ns2.ou.nl
NS in the zone
dns.ou.nl, ns.ou.nl, ns2.ou.nl
NameserverAddressesNetwork (AS)Glue
dns.ou.nl145.20.126.14 2001:610:338:1030::126:14AS1103 SURFNET-NL - SURF B.V., NL AS1103 SURFNET-NL - SURF B.V., NL145.20.126.14 2001:610:338:1030::126:14
ns.ou.nl145.20.126.12 2001:610:338:1030::126:12AS1103 SURFNET-NL - SURF B.V., NL AS1103 SURFNET-NL - SURF B.V., NL145.20.126.12 2001:610:338:1030::126:12
ns2.ou.nl145.20.126.13 2001:610:338:1030::126:13AS1103 SURFNET-NL - SURF B.V., NL AS1103 SURFNET-NL - SURF B.V., NL145.20.126.13 2001:610:338:1030::126:13

Checks

  • ✓ 3 nameservers #6
    Delegated to dns.ou.nl, ns.ou.nl, ns2.ou.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: dns.ou.nl, ns.ou.nl, ns2.ou.nl.
  • ✓ All names resolve #9
    Every nameserver name has an address and is not an alias.
  • !
    Nameservers in one network
    all IPv4 addresses are in 145.20.126.0/24; all IPv6 addresses are in 2001:610:338::/48. A single network failure takes all nameservers down; RFC 2182 recommends topologically separate networks (anycast setups are an exception).
    #10
  • i
    All nameservers in one AS
    All nameserver addresses are announced by one network operator (AS1103 (SURFNET-NL - SURF B.V., NL): 6 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 .nl
    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
  • ✓ All reachable over IPv6 #13
    Every nameserver has an IPv6 address.

Nameservers

fail

3 of 6 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
dns.ou.nl 145.20.126.14NOERROR, 14 ms, authoritativenoyes / yesrefused-
dns.ou.nl 2001:610:338:1030::126:14no responsenono / no--
ns.ou.nl 145.20.126.12NOERROR, 15 ms, authoritativenoyes / yesrefusedBIND
ns.ou.nl 2001:610:338:1030::126:12no responsenono / no--
ns2.ou.nl 145.20.126.13NOERROR, 15 ms, authoritativenoyes / yesrefusedBIND
ns2.ou.nl 2001:610:338:1030::126:13no responsenono / no--

Checks

  • ✗
    Nameservers not responding
    These addresses did not answer, so resolvers waste time on timeouts: dns.ou.nl (2001:610:338:1030::126:14): read udp [2a01:4f8:1c1c:eebf::1]:42069->[2001:610:338:1030::126:14]:53: i/o timeout; ns.ou.nl (2001:610:338:1030::126:12): read udp [2a01:4f8:1c1c:eebf::1]:36975->[2001:610:338:1030::126:12]:53: i/o timeout; ns2.ou.nl (2001:610:338:1030::126:13): read udp [2a01:4f8:1c1c:eebf::1]:53838->[2001:610:338:1030::126:13]: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: ns.ou.nl: "BIND"; ns2.ou.nl: "BIND".
    #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 2015964350 · primary dns.ou.nl

Found

Primary (MNAME)
dns.ou.nl
Contact (RNAME)
postmaster.ou.nl
Serial
2015964350
Refresh / retry
14400 s / 1440 s
Expire
604800 s
Negative TTL
86400 s

Serial per nameserver

NameserverSerial
dns.ou.nl (145.20.126.14)2015964350
ns.ou.nl (145.20.126.12)2015964350
ns2.ou.nl (145.20.126.13)2015964350

Checks

  • ✓ Serial 2015964350 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 4h, retry 24m, expire 7d, negative TTL 1d.
  • ✓ Primary is a public nameserver #24
    The primary nameserver dns.ou.nl is one of the listed nameservers.
  • ✓ Contact postmaster@ou.nl #25
    The SOA RNAME postmaster.ou.nl means postmaster@ou.nl.
  • ✓ Timestamp serial #26
    The serial 2015964350 is a Unix timestamp (2033-11-18 22:05 UTC).

DNSSEC

info

Signed, DS published at parent

Found

Validated by resolver
yes
Denial of existence
NSEC
Signatures valid until
25 October 2026

DS at the parent

Key tagAlgorithmDigestMatches a key
41686RSASHA256 (8)SHA256 4D54A4FE1BF2D7F3…NO
17839RSASHA256 (8)SHA256 D202079271D9BB7C…yes

DNSKEY in the zone

Key tagRoleAlgorithm
37926ZSK (256)RSASHA256 (8)
5379ZSK (256)RSASHA256 (8)
17839KSK (257)RSASHA256 (8)
9304ZSK (256)RSASHA256 (8)

Checks

  • ✓ Signed and validated #27
    The zone is signed, the parent publishes a DS record, and the resolver validates the answers.
  • i
    Unused DS records
    These DS records match no key in the zone: key tag 41686 (SHA256). That is normal during a key rollover; otherwise remove them.
    #28
  • ✓ Modern algorithms #29
    Key algorithms: RSASHA256 (8).
  • ✓ Short-lived signatures (online signing) #30
    Signatures are valid for 97h0m0s and created on demand; the current one was made at 2026-10-21 03:21 UTC and expires at 2026-10-25 04:21 UTC.
  • i
    NSEC
    The zone uses NSEC, so its full contents can be listed by walking the NSEC chain. That is fine unless the names are sensitive.
    #31

Records

warn

18 records at the apex

Found

Read from
145.20.126.14:53
TypeValueTTL
SOAdns.ou.nl. postmaster.ou.nl. 2015964350 14400 1440 604800 86400172800
NSdns.ou.nl.172800
NSns2.ou.nl.172800
NSns.ou.nl.172800
A145.20.124.14860
MX0 ou-nl.mail.protection.outlook.com.3600
MX20 mailserv2.ou.nl.3600
MX10 relay.ou.nl.3600
TXT"4QRKLgYVvy3472d/Nsab+HVbraq0nLSoZxfpcc2GBDkVS0IGoDqn0swseCEEFa79EEuZ4fwRWRkcU9azjEOshw=="3600
TXT"MS=D9FA522DB0A593F330B3C81ADF4B4371B7C388CC"3600
TXT"MS=ms81132576"3600
TXT"adobe-idp-site-verification=b509ce18e838a8e9b82da8dcdbb762a5b4322f2b736ec94ae9a5925e3ca9e37b"3600
TXT"d365mktkey=jJ9sqCV2Xujx0xUicyyubd09sSMxyxS80b7VhwKsXKwx"3600
TXT"ms-domain-verification=5bbde023-f788-4f59-aca9-0c3dc6fc1bd5"3600
TXT"abuseipdb-verification=Cdp0Mzoj"3600
TXT"HARICA-Bl1KpyxS8WgDRFGaLKA"3600
TXT"v=spf1 mx ip4:145.20.126.12/31 ip6:2001:610:338:1030::126:12/127 ip4:194.187.45.0/26 include:spf.protection.outlook.com -all"3600
TXT"google-site-verification=qwghcgXEcQ7PDmgOKsNnVjEo2DD583UKdYAKoMUY_zg"3600

Checks

  • !
    Very low TTLs
    These records have a TTL below 5m, causing extra queries and slower lookups: A (1m). Low TTLs are useful just before a planned change. The NS TTL at the parent is 1h and in the zone 2d; 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.
  • 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