ubuntu.com

Checked 22 October 2026, 11:14 UTC · via 8.8.8.8
!Passed with warnings
22 passed 5 warnings 0 failed 4 info

Registration

info

.com generic · MarkMonitor Inc. · expires 2028-05-29

Found

TLD
.com (generic)
ICANN policies apply
yes
Registrar
MarkMonitor Inc.
Registered
29 May 2004
Last changed
27 April 2026
Expires
29 May 2028
Status
client delete prohibited, client transfer prohibited, client update prohibited
Registry nameservers
ns1.canonical.com, ns2.canonical.com, ns3.canonical.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 2028-05-29 #3
    The registration is valid until 2028-05-29 (585 days).
  • ✓ Transfer locked #4
    Registry status: client delete prohibited, client transfer prohibited, client update prohibited.
  • ✓ Registry and delegation match #5
    The nameservers registered at the registry are the ones published in DNS.

Delegation

warn

ns1.canonical.com, ns2.canonical.com, ns3.canonical.com

Found

Parent zone
com
Delegation from
a.gtld-servers.net (192.5.6.30)
NS at the parent
ns1.canonical.com, ns2.canonical.com, ns3.canonical.com
NS in the zone
ns1.canonical.com, ns2.canonical.com, ns3.canonical.com
NameserverAddressesNetwork (AS)Glue
ns1.canonical.com185.125.190.65 2620:2d:4000:1::43AS41231 CANONICAL-AS - Canonical Group Limited, GB AS41231 CANONICAL-AS - Canonical Group Limited, GB185.125.190.65 2620:2d:4000:1::43
ns2.canonical.com185.125.190.66 2620:2d:4000:1::44AS41231 CANONICAL-AS - Canonical Group Limited, GB AS41231 CANONICAL-AS - Canonical Group Limited, GB185.125.190.66 2620:2d:4000:1::44
ns3.canonical.com185.125.190.66AS41231 CANONICAL-AS - Canonical Group Limited, GB185.125.190.65 185.125.190.66

Checks

  • ✓ 3 nameservers #6
    Delegated to ns1.canonical.com, ns2.canonical.com, ns3.canonical.com.
  • ✓ Parent and zone agree #7
    The parent delegation and the zone's NS records list the same nameservers.
  • !
    Glue differs from the zone
    The addresses at the parent (glue) differ from the addresses in the zone: ns3.canonical.com (glue 185.125.190.65, 185.125.190.66, zone 185.125.190.66). Update the glue at your registrar.
    #8
  • ✓ All names resolve #9
    Every nameserver name has an address and is not an alias.
  • !
    Nameservers in one network
    all IPv4 addresses are in 185.125.190.0/24; all IPv6 addresses are in 2620:2d:4000::/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 (AS41231 (CANONICAL-AS - Canonical Group Limited, GB): 5 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
  • i
    Partly IPv6
    These nameservers have no IPv6 address: ns3.canonical.com.
    #13

Nameservers

warn

5 of 5 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
ns1.canonical.com 185.125.190.65NOERROR, 17 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.22.04.7-Ubuntu
ns1.canonical.com 2620:2d:4000:1::43NOERROR, 44 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.22.04.7-Ubuntu
ns2.canonical.com 185.125.190.66NOERROR, 23 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.22.04.7-Ubuntu
ns2.canonical.com 2620:2d:4000:1::44NOERROR, 46 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.22.04.7-Ubuntu
ns3.canonical.com 185.125.190.66NOERROR, 22 ms, authoritativenoyes / yesrefused9.18.39-0ubuntu0.22.04.7-Ubuntu

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.canonical.com: "9.18.39-0ubuntu0.22.04.7-Ubuntu"; ns2.canonical.com: "9.18.39-0ubuntu0.22.04.7-Ubuntu"; ns3.canonical.com: "9.18.39-0ubuntu0.22.04.7-Ubuntu". 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 2018067131 · primary ns1.canonical.com

Found

Primary (MNAME)
ns1.canonical.com
Contact (RNAME)
hostmaster.canonical.com
Serial
2018067131
Refresh / retry
10800 s / 3600 s
Expire
604800 s
Negative TTL
3600 s

Serial per nameserver

NameserverSerial
ns1.canonical.com (185.125.190.65)2018067131
ns1.canonical.com (2620:2d:4000:1::43)2018067131
ns2.canonical.com (185.125.190.66)2018067131
ns2.canonical.com (2620:2d:4000:1::44)2018067131
ns3.canonical.com (185.125.190.66)2018067131

Checks

  • ✓ Serial 2018067131 everywhere #22
    All nameservers serve the same version of the zone.
  • ✓ Timers within recommendations #23
    SOA refresh 3h, retry 1h, expire 7d, negative TTL 1h.
  • ✓ Primary is a public nameserver #24
    The primary nameserver ns1.canonical.com is one of the listed nameservers.
  • ✓ Contact hostmaster@canonical.com #25
    The SOA RNAME hostmaster.canonical.com means hostmaster@canonical.com.
  • ✓ Timestamp serial #26
    The serial 2018067131 is a Unix timestamp (2033-12-13 06:12 UTC).

DNSSEC

warn

Not signed

Found

Validated by resolver
no

Checks

  • !
    Not signed
    The zone is not signed with DNSSEC, so answers can be spoofed. Enable DNSSEC at your DNS provider and publish the DS record at your registrar.
    #27

Records

warn

20 records at the apex

Found

Read from
185.125.190.65:53
TypeValueTTL
SOAns1.canonical.com. hostmaster.canonical.com. 2018067131 10800 3600 604800 36003600
NSns1.canonical.com.172800
NSns3.canonical.com.172800
NSns2.canonical.com.172800
A185.125.190.2960
A185.125.190.2160
A185.125.190.2060
AAAA2620:2d:4000:1::2860
AAAA2620:2d:4000:1::2760
AAAA2620:2d:4000:1::2660
MX10 mx.ubuntu.com.3600
TXT"v=spf1 include:_spf.canonical.com include:spf.forwardemail.net ~all"600
TXT"google-site-verification=8CcvY6fsgRbiFk2nyEaiA9rE-ykXOcWUPjJKlO6P4vk"600
TXT"forward-email-site-verification=6IsURgl2t7"600
CAA0 issue "digicert.com"3600
CAA0 iodef "mailto:is-admin@canonical.com"3600
CAA0 issue "letsencrypt.org; accounturi=https://acme-v01.api.letsencrypt.org/acme/reg/32541290"3600
CAA0 issuewild "digicert.com"3600
CAA0 issuewild "letsencrypt.org"3600
CAA0 issue "letsencrypt.org"3600

Checks

  • !
    Very low TTLs
    These records have a TTL below 5m, causing extra queries and slower lookups: A (1m), AAAA (1m). Low TTLs are useful just before a planned change.
    #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: digicert.com, letsencrypt.org.