mdpi.com

Checked 22 October 2026, 09:44 UTC · via 8.8.8.8
!Passed with warnings
26 passed 3 warnings 0 failed 5 info

Registration

info

.com generic · Network Solutions, LLC · expires 2034-05-12

Found

TLD
.com (generic)
ICANN policies apply
yes
Registrar
Network Solutions, LLC
Registered
19 December 2003
Last changed
12 May 2024
Expires
12 May 2034
Status
client transfer prohibited
Registry nameservers
duke.ns.cloudflare.com, tia.ns.cloudflare.com
RDAP server
https://rdap.verisign.com/com/v1/

Checks

  • i
    .com is a generic TLD (gTLD)
    Generic TLD under an ICANN registry agreement: ICANN-accredited registrars, UDRP and RDAP apply.
    #1
  • ✓ TLD delegated and signed #2
    .com is delegated in the root zone and DNSSEC-signed.
  • ✓ Expires on 2034-05-12 #3
    The registration is valid until 2034-05-12 (2759 days).
  • ✓ Transfer locked #4
    Registry status: client transfer prohibited.
  • ✓ Registry and delegation match #5
    The nameservers registered at the registry are the ones published in DNS.

Delegation

info

duke.ns.cloudflare.com, tia.ns.cloudflare.com

Found

Parent zone
com
Delegation from
a.gtld-servers.net (192.5.6.30)
NS at the parent
duke.ns.cloudflare.com, tia.ns.cloudflare.com
NS in the zone
duke.ns.cloudflare.com, tia.ns.cloudflare.com
NameserverAddressesNetwork (AS)Glue
duke.ns.cloudflare.com108.162.193.110 173.245.59.110 172.64.33.110 2606:4700:58::adf5:3b6e 2a06:98c1:50::ac40:216e 2803:f800:50::6ca2:c16eAS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US108.162.193.110 172.64.33.110 173.245.59.110 2606:4700:58::adf5:3b6e 2803:f800:50::6ca2:c16e 2a06:98c1:50::ac40:216e
tia.ns.cloudflare.com172.64.32.229 108.162.192.229 173.245.58.229 2803:f800:50::6ca2:c0e5 2a06:98c1:50::ac40:20e5 2606:4700:50::adf5:3ae5AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US108.162.192.229 172.64.32.229 173.245.58.229 2606:4700:50::adf5:3ae5 2803:f800:50::6ca2:c0e5 2a06:98c1:50::ac40:20e5

Checks

  • i
    2 nameservers
    Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: duke.ns.cloudflare.com, tia.ns.cloudflare.com.
    #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 different networks #10
    The nameservers are spread over 6 IPv4 /24s and 4 IPv6 /48s.
  • i
    All nameservers in one AS
    All nameserver addresses are announced by one network operator (AS13335 (CLOUDFLARENET - Cloudflare, Inc., US): 12 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 .com
    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

12 of 12 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
duke.ns.cloudflare.com 108.162.193.110NOERROR, 14 ms, authoritativenoyes / yesrefused2026.10.2
duke.ns.cloudflare.com 173.245.59.110NOERROR, 14 ms, authoritativenoyes / yesrefused2026.10.2
duke.ns.cloudflare.com 172.64.33.110NOERROR, 17 ms, authoritativenoyes / yesrefused2026.10.2
duke.ns.cloudflare.com 2606:4700:58::adf5:3b6eNOERROR, 14 ms, authoritativenoyes / yesrefused2026.10.2
duke.ns.cloudflare.com 2a06:98c1:50::ac40:216eNOERROR, 15 ms, authoritativenoyes / yesrefused2026.10.2
duke.ns.cloudflare.com 2803:f800:50::6ca2:c16eNOERROR, 14 ms, authoritativenoyes / yesrefused2026.10.2
tia.ns.cloudflare.com 172.64.32.229NOERROR, 14 ms, authoritativenoyes / yesrefused2026.10.2
tia.ns.cloudflare.com 108.162.192.229NOERROR, 14 ms, authoritativenoyes / yesrefused2026.10.2
tia.ns.cloudflare.com 173.245.58.229NOERROR, 15 ms, authoritativenoyes / yesrefused2026.10.2
tia.ns.cloudflare.com 2803:f800:50::6ca2:c0e5NOERROR, 14 ms, authoritativenoyes / yesrefused2026.10.2
tia.ns.cloudflare.com 2a06:98c1:50::ac40:20e5NOERROR, 14 ms, authoritativenoyes / yesrefused2026.10.2
tia.ns.cloudflare.com 2606:4700:50::adf5:3ae5NOERROR, 15 ms, authoritativenoyes / yesrefused2026.10.2

Checks

  • ✓ All respond #14
    All 12 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: duke.ns.cloudflare.com: "2026.10.2"; tia.ns.cloudflare.com: "2026.10.2". 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 2417609556 · primary duke.ns.cloudflare.com

Found

Primary (MNAME)
duke.ns.cloudflare.com
Contact (RNAME)
dns.cloudflare.com
Serial
2417609556
Refresh / retry
10000 s / 2400 s
Expire
604800 s
Negative TTL
1800 s

Serial per nameserver

NameserverSerial
duke.ns.cloudflare.com (108.162.193.110)2417609556
duke.ns.cloudflare.com (173.245.59.110)2417609556
duke.ns.cloudflare.com (172.64.33.110)2417609556
duke.ns.cloudflare.com (2606:4700:58::adf5:3b6e)2417609556
duke.ns.cloudflare.com (2a06:98c1:50::ac40:216e)2417609556
duke.ns.cloudflare.com (2803:f800:50::6ca2:c16e)2417609556
tia.ns.cloudflare.com (172.64.32.229)2417609556
tia.ns.cloudflare.com (108.162.192.229)2417609556
tia.ns.cloudflare.com (173.245.58.229)2417609556
tia.ns.cloudflare.com (2803:f800:50::6ca2:c0e5)2417609556
tia.ns.cloudflare.com (2a06:98c1:50::ac40:20e5)2417609556
tia.ns.cloudflare.com (2606:4700:50::adf5:3ae5)2417609556

Checks

  • ✓ Serial 2417609556 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 2h46m40s, retry 40m, expire 7d, negative TTL 30m.
  • ✓ Primary is a public nameserver #24
    The primary nameserver duke.ns.cloudflare.com is one of the listed nameservers.
  • ✓ Contact dns@cloudflare.com #25
    The SOA RNAME dns.cloudflare.com means dns@cloudflare.com.
  • ✓ Timestamp serial #26
    The serial 2417609556 is a Unix timestamp (2046-08-11 14:12 UTC).

DNSSEC

warn

Signed, but no DS at parent

Found

Validated by resolver
no
Denial of existence
NSEC
Signatures valid until
23 October 2026

DNSKEY in the zone

Key tagRoleAlgorithm
2371KSK (257)ECDSAP256SHA256 (13)
34505ZSK (256)ECDSAP256SHA256 (13)

Checks

  • !
    Signed but not delegated securely
    The zone is signed but the parent has no DS record, so the signatures are not used. Publish the DS record at your registrar.
    #27
  • ✓ Modern algorithms #29
    Key algorithms: ECDSAP256SHA256 (13).
  • ✓ Short-lived signatures (online signing) #30
    Signatures are valid for 50h0m0s and created on demand; the current one was made at 2026-10-21 08:44 UTC and expires at 2026-10-23 10:44 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

29 records at the apex

Found

Read from
108.162.193.110:53
TypeValueTTL
SOAduke.ns.cloudflare.com. dns.cloudflare.com. 2417609556 10000 2400 604800 18001800
NSduke.ns.cloudflare.com.86400
NStia.ns.cloudflare.com.86400
A23.222.250.50
A23.222.250.270
AAAA2a02:26f0:9100:20::17c0:76ca20
AAAA2a02:26f0:9100:20::17c0:76d520
MX10 mail.mdpi.com.300
TXT"MS=7983DA5502DEB40953AE07AF7287CD4DA1D92273"300
TXT"MS=ms22287815"300
TXT"anthropic-domain-verification-0gqk0p=F7Zo1HH7mxxuCicADqZIVVoxw"300
TXT"atlassian-domain-verification=B8vS1pMclo3CtNoM1lEBx67CaALcw0VrjLBCUcyidI3VnIvUECd752eWuaJ6ni3H"300
TXT"google-site-verification=5HGq1F7H_WX_Q3Qf85UZh5dEVC0fS5UeSizLzGTyw40"300
TXT"google-site-verification=8ILGAlmpYZT-asFMBkmbeopoNQ-tmhDNmTNPiAFMbrk"300
TXT"teamtailor-domain-verification=a283d2897d2a3994d80f17065454404b"300
TXT"teamtailor=3bfe85f552a3915e3ad4b23af293ac47"300
TXT"teamtailor=58fdad9a36360e0b3926144848860501"300
TXT"teamtailor=77e8a587477a29b8c3593dc9495ecb73"300
TXT"teamtailor=8c49eb3de25673dd2d38fea4e2dcce62"300
TXT"teamtailor=bd3f6e65bf12733c2239b3551a5120b7"300
TXT"teamtailor=ea0bfb03d594f650556ecf8916782cc6"300
TXT"v=spf1 mx include:spf.mdpi.com include:25322191.spf10.hubspotemail.net include:spf.protection.outlook.com -all"300
TXT"yahoo-verification-key=puT8WI8WEun8VA7UT6avJY4Ck+DwplIauEM9YJmzOB4="300
CAA0 issue "amazonaws.com"300
CAA0 issue "certainly.com"300
CAA0 issue "digicert.com"300
CAA0 issue "letsencrypt.org"300
CAA0 issue "pki.goog"300
CAA0 issue "zerossl.com"300

Checks

  • !
    Very low TTLs
    These records have a TTL below 5m, causing extra queries and slower lookups: A (0s), AAAA (20s). Low TTLs are useful just before a planned change. The NS TTL at the parent is 2d and in the zone 1d; 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: amazonaws.com, certainly.com, digicert.com, letsencrypt.org, pki.goog, zerossl.com.