Domain report: universonline.nl

Registration

info

.nl country-code

Found

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

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

#3

Delegation

warn

ns1.uvt.nl, ns2.uvt.nl

Found

Parent zone: nl
Delegation from: ns1.dns.nl (194.0.28.53)
NS at the parent: ns1.uvt.nl, ns2.uvt.nl
NS in the zone: ns1.uvt.nl, ns2.uvt.nl

Nameserver	Addresses	Network (AS)	Glue
ns1.uvt.nl	137.56.247.39 2001:610:1410:0:9b5d:fd1c:8983:3687	AS1103 SURFNET-NL - SURF B.V., NL AS1103 SURFNET-NL - SURF B.V., NL	137.56.247.39 2001:610:1410:0:9b5d:fd1c:8983:3687
ns2.uvt.nl	137.56.247.40 2001:610:1410:0:28b:f453:70ab:663b	AS1103 SURFNET-NL - SURF B.V., NL AS1103 SURFNET-NL - SURF B.V., NL	137.56.247.40 2001:610:1410:0:28b:f453:70ab:663b

Checks

i

2 nameservers

Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: ns1.uvt.nl, ns2.uvt.nl.

#6
✓ 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 one network

all IPv4 addresses are in 137.56.247.0/24; all IPv6 addresses are in 2001:610:1410::/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): 4 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

warn

4 of 4 addresses answer authoritatively

Found

Nameserver	Answer	Recursion	TCP / EDNS	AXFR	Version
ns1.uvt.nl 137.56.247.39	NOERROR, 13 ms, authoritative	no	yes / yes	refused	NSD 4.3.5
ns1.uvt.nl 2001:610:1410:0:9b5d:fd1c:8983:3687	NOERROR, 13 ms, authoritative	no	yes / yes	refused	NSD 4.3.5
ns2.uvt.nl 137.56.247.40	NOERROR, 13 ms, authoritative	no	yes / yes	refused	NSD 4.3.5
ns2.uvt.nl 2001:610:1410:0:28b:f453:70ab:663b	NOERROR, 14 ms, authoritative	no	yes / yes	refused	NSD 4.3.5

Checks

✓ All respond #14

All 4 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.uvt.nl: "NSD 4.3.5"; ns2.uvt.nl: "NSD 4.3.5". 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 2026102200 · primary ns1.uvt.nl

Found

Primary (MNAME): ns1.uvt.nl
Contact (RNAME): hostmaster.uvt.nl
Serial: 2026102200
Refresh / retry: 28800 s / 14400 s
Expire: 604800 s
Negative TTL: 300 s

Serial per nameserver

Nameserver	Serial
ns1.uvt.nl (137.56.247.39)	2026102200
ns1.uvt.nl (2001:610:1410:0:9b5d:fd1c:8983:3687)	2026102200
ns2.uvt.nl (137.56.247.40)	2026102200
ns2.uvt.nl (2001:610:1410:0:28b:f453:70ab:663b)	2026102200

Checks

✓ Serial 2026102200 everywhere #22

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

SOA refresh 8h, retry 4h, expire 7d, negative TTL 5m.
✓ Primary is a public nameserver #24

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

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

The serial 2026102200 follows the YYYYMMDDnn convention (2026-10-22).

DNSSEC

warn

Signed, DS published at parent

Found

Validated by resolver: yes
Denial of existence: NSEC3
NSEC3: 5 iterations, 8-byte salt
Signatures valid until: 4 November 2026

DS at the parent

Key tag	Algorithm	Digest	Matches a key
29342	RSASHA256 (8)	SHA256 B3572400311477A7…	yes

DNSKEY in the zone

Key tag	Role	Algorithm
29342	KSK (257)	RSASHA256 (8)
48285	ZSK (256)	RSASHA256 (8)
5856	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 29342 (SHA256).
✓ Modern algorithms #29

Key algorithms: RSASHA256 (8).
✓ Signatures valid until 2026-11-04 #30

The earliest DNSKEY/SOA signature expires at 2026-11-04 11:16 UTC.
!

NSEC3 with extra iterations or salt

NSEC3 uses 5 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

warn

20 records at the apex

Found

Read from: 137.56.247.39:53

Type	Value	TTL
SOA	ns1.uvt.nl. hostmaster.uvt.nl. 2026102200 28800 14400 604800 300	3600
NS	ns1.uvt.nl.	3600
NS	ns2.uvt.nl.	3600
A	162.159.135.42	60
MX	0 universonline-nl.mail.protection.outlook.com.	60
TXT	"Universiteit van Tilburg"	60
TXT	"Tilburg University"	60
TXT	"Warandelaan 2, Tilburg, The Netherlands"	60
TXT	"P.O.box 90153, 5000 LE Tilburg, The Netherlands"	60
TXT	"phone: +31-13-4669111"	60
TXT	"MS=ms85802851"	60
TXT	"google-site-verification=4j05UDB3Kni8moZ44D9h9dVtcBinCMHhjdbLUv3SOTA"	60
TXT	"v=spf1 include:spf.protection.outlook.com -all"	60
CAA	0 iodef "mailto:ssl@uvt.nl"	3600
CAA	0 issue "letsencrypt.org"	3600
CAA	0 issue "digicert.com"	3600
CAA	0 issue "sectigo.com"	3600
CAA	0 issue "pki.goog"	3600
CAA	0 issue "harica.gr"	3600
CAA	0 issue "amazon.com"	3600

Checks

!

Very low TTLs

These records have a TTL below 5m, causing extra queries and slower lookups: A (1m), MX (1m). Low TTLs are useful just before a planned change.

#32
✓ No CNAME at the apex #33

The zone apex has no CNAME record.
i

Wildcard record

A random name under the zone resolves, so there is a wildcard (*) record. Typos and non-existent hosts resolve too, which can confuse mail and certificate checks.

#34
✓ CAA restricts issuance #35

Certificates may be issued by: letsencrypt.org, digicert.com, sectigo.com, pki.goog, harica.gr, amazon.com.