lynda.com

Checked 22 October 2026, 09:41 UTC · via 8.8.8.8
!Passed with warnings
25 passed 4 warnings 0 failed 2 info

Registration

info

.com generic · MarkMonitor Inc. · expires 2027-10-30

Found

TLD
.com (generic)
ICANN policies apply
yes
Registrar
MarkMonitor Inc.
Registered
21 December 1995
Last changed
28 September 2026
Expires
30 October 2027
Status
client delete prohibited, client transfer prohibited, client update prohibited, server delete prohibited, server transfer prohibited, server update prohibited
Registry nameservers
dns1.p09.nsone.net, dns2.p09.nsone.net, dns3.p09.nsone.net, dns4.p09.nsone.net, ns1-42.azure-dns.com, ns2-42.azure-dns.net, ns3-42.azure-dns.org, ns4-42.azure-dns.info
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 2027-10-30 #3
    The registration is valid until 2027-10-30 (373 days).
  • ✓ Transfer locked #4
    Registry status: client delete prohibited, client transfer prohibited, client update prohibited, server delete prohibited, server transfer prohibited, server update prohibited.
  • ✓ Registry and delegation match #5
    The nameservers registered at the registry are the ones published in DNS.

Delegation

info

dns1.p09.nsone.net, dns2.p09.nsone.net, dns3.p09.nsone.net, dns4.p09.nsone.net, ns1-42.azure-dns.com, ns2-42.azure-dns.net, ns3-42.azure-dns.org, ns4-42.azure-dns.info

Found

Parent zone
com
Delegation from
a.gtld-servers.net (192.5.6.30)
NS at the parent
dns1.p09.nsone.net, dns2.p09.nsone.net, dns3.p09.nsone.net, dns4.p09.nsone.net, ns1-42.azure-dns.com, ns2-42.azure-dns.net, ns3-42.azure-dns.org, ns4-42.azure-dns.info
NS in the zone
dns1.p09.nsone.net, dns2.p09.nsone.net, dns3.p09.nsone.net, dns4.p09.nsone.net, ns1-42.azure-dns.com, ns2-42.azure-dns.net, ns3-42.azure-dns.org, ns4-42.azure-dns.info
NameserverAddressesNetwork (AS)Glue
dns1.p09.nsone.net198.51.44.9 2620:4d:4000:6259:7:9:0:1AS62597 NSONE - NSONE Inc, US AS62597 NSONE - NSONE Inc, US-
dns2.p09.nsone.net198.51.45.9 2a00:edc0:6259:7:9::2AS62597 NSONE - NSONE Inc, US AS62597 NSONE - NSONE Inc, US-
dns3.p09.nsone.net198.51.44.73 2620:4d:4000:6259:7:9:0:3AS62597 NSONE - NSONE Inc, US AS62597 NSONE - NSONE Inc, US-
dns4.p09.nsone.net198.51.45.73 2a00:edc0:6259:7:9::4AS62597 NSONE - NSONE Inc, US AS62597 NSONE - NSONE Inc, US-
ns1-42.azure-dns.com150.171.10.42AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation, US150.171.10.42
ns2-42.azure-dns.net150.171.16.42AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation, US-
ns3-42.azure-dns.org13.107.222.42AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation, US-
ns4-42.azure-dns.info13.107.206.42AS8075 MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation, US-

Checks

  • ✓ 8 nameservers #6
    Delegated to dns1.p09.nsone.net, dns2.p09.nsone.net, dns3.p09.nsone.net, dns4.p09.nsone.net, ns1-42.azure-dns.com, ns2-42.azure-dns.net, ns3-42.azure-dns.org, ns4-42.azure-dns.info.
  • ✓ 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 2 IPv6 /48s.
  • ✓ 2 autonomous systems #11
    The nameservers are spread over: AS62597 (NSONE - NSONE Inc, US): 8 addresses; AS8075 (MICROSOFT-CORP-MSN-AS-BLOCK - Microsoft Corporation, US): 4 addresses.
  • ✓ Nameserver names under 4 TLDs #12
    Nameserver names use the TLDs .com, .info, .net, .org.
  • i
    Partly IPv6
    These nameservers have no IPv6 address: ns1-42.azure-dns.com, ns2-42.azure-dns.net, ns3-42.azure-dns.org, ns4-42.azure-dns.info.
    #13

Nameservers

warn

12 of 12 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
dns1.p09.nsone.net 198.51.44.9NOERROR, 5 ms, authoritativenoyes / yesrefused19dd46e347df36b70933bf2be8023258586586a9
dns1.p09.nsone.net 2620:4d:4000:6259:7:9:0:1NOERROR, 7 ms, authoritativenoyes / yesrefused19dd46e347df36b70933bf2be8023258586586a9
dns2.p09.nsone.net 198.51.45.9NOERROR, 5 ms, authoritativenoyes / yesrefused19dd46e347df36b70933bf2be8023258586586a9
dns2.p09.nsone.net 2a00:edc0:6259:7:9::2NOERROR, 5 ms, authoritativenoyes / yesrefused19dd46e347df36b70933bf2be8023258586586a9
dns3.p09.nsone.net 198.51.44.73NOERROR, 7 ms, authoritativenoyes / yesrefused19dd46e347df36b70933bf2be8023258586586a9
dns3.p09.nsone.net 2620:4d:4000:6259:7:9:0:3NOERROR, 7 ms, authoritativenoyes / yesrefused19dd46e347df36b70933bf2be8023258586586a9
dns4.p09.nsone.net 198.51.45.73NOERROR, 5 ms, authoritativenoyes / yesrefused19dd46e347df36b70933bf2be8023258586586a9
dns4.p09.nsone.net 2a00:edc0:6259:7:9::4NOERROR, 4 ms, authoritativenoyes / yesrefused19dd46e347df36b70933bf2be8023258586586a9
ns1-42.azure-dns.com 150.171.10.42NOERROR, 4 ms, authoritativenoyes / yesrefused-
ns2-42.azure-dns.net 150.171.16.42NOERROR, 4 ms, authoritativenoyes / yesrefusedKnot DNS 3.1.2.1770717641.d6b376aff
ns3-42.azure-dns.org 13.107.222.42NOERROR, 4 ms, authoritativenoyes / yesrefused-
ns4-42.azure-dns.info 13.107.206.42NOERROR, 4 ms, authoritativenoyes / yesrefusedKnot DNS 3.1.2.1770717641.d6b376aff

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: ns2-42.azure-dns.net: "Knot DNS 3.1.2.1770717641.d6b376aff"; ns4-42.azure-dns.info: "Knot DNS 3.1.2.1770717641.d6b376aff". 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

warn

serial 1653609948 · primary dns1.p09.nsone.net

Found

Primary (MNAME)
dns1.p09.nsone.net
Contact (RNAME)
hostmaster.linkedin.com
Serial
1653609948
Refresh / retry
3600 s / 600 s
Expire
604800 s
Negative TTL
60 s

Serial per nameserver

NameserverSerial
dns1.p09.nsone.net (198.51.44.9)1653609948
dns1.p09.nsone.net (2620:4d:4000:6259:7:9:0:1)1653609948
dns2.p09.nsone.net (198.51.45.9)1653609948
dns2.p09.nsone.net (2a00:edc0:6259:7:9::2)1653609948
dns3.p09.nsone.net (198.51.44.73)1653609948
dns3.p09.nsone.net (2620:4d:4000:6259:7:9:0:3)1653609948
dns4.p09.nsone.net (198.51.45.73)1653609948
dns4.p09.nsone.net (2a00:edc0:6259:7:9::4)1653609948
ns1-42.azure-dns.com (150.171.10.42)12
ns2-42.azure-dns.net (150.171.16.42)12
ns3-42.azure-dns.org (13.107.222.42)12
ns4-42.azure-dns.info (13.107.206.42)12

Checks

  • !
    Serials differ
    The nameservers serve different versions of the zone: 12 on ns1-42.azure-dns.com (150.171.10.42), ns2-42.azure-dns.net (150.171.16.42), ns3-42.azure-dns.org (13.107.222.42), ns4-42.azure-dns.info (13.107.206.42); 1653609948 on dns1.p09.nsone.net (198.51.44.9), dns1.p09.nsone.net (2620:4d:4000:6259:7:9:0:1), dns2.p09.nsone.net (198.51.45.9), dns2.p09.nsone.net (2a00:edc0:6259:7:9::2), dns3.p09.nsone.net (198.51.44.73), dns3.p09.nsone.net (2620:4d:4000:6259:7:9:0:3), dns4.p09.nsone.net (198.51.45.73), dns4.p09.nsone.net (2a00:edc0:6259:7:9::4). This is normal for a few minutes after a change; if it lasts, zone transfers to the secondaries are failing.
    #22
  • !
    Unusual SOA timers
    negative caching TTL (minimum) 1m is outside 5m–1d (RFC 2308 recommends 1–3 hours). Current values: refresh 1h, retry 10m, expire 7d, negative TTL 1m.
    #23
  • ✓ Primary is a public nameserver #24
    The primary nameserver dns1.p09.nsone.net is one of the listed nameservers.
  • ✓ Contact hostmaster@linkedin.com #25
    The SOA RNAME hostmaster.linkedin.com means hostmaster@linkedin.com.
  • ✓ Timestamp serial #26
    The serial 1653609948 is a Unix timestamp (2022-05-27 00:05 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

pass

25 records at the apex

Found

Read from
198.51.44.9:53
TypeValueTTL
SOAdns1.p09.nsone.net. hostmaster.linkedin.com. 1653609948 3600 600 604800 603600
NSdns1.p09.nsone.net.86400
NSdns2.p09.nsone.net.86400
NSdns3.p09.nsone.net.86400
NSdns4.p09.nsone.net.86400
NSns1-42.azure-dns.com.86400
NSns2-42.azure-dns.net.86400
NSns3-42.azure-dns.org.86400
NSns4-42.azure-dns.info.86400
A130.211.32.143600
AAAA2600:1901:0:d5ad::3600
MX10 mail-1.linkedin.com.300
MX15 mail-2.linkedin.com.300
MX15 mail-d.linkedin.com.300
MX20 mail-a.linkedin.com.300
MX20 mail-c.linkedin.com.300
MX20 mail.linkedin.com.300
TXT"MS=ms48400913"300
TXT"MS=ms56649312"300
TXT"_6xxhaq98xaeb80aazhyzt7z0gdcbn8k"300
TXT"_xqfeq9o3rn2e8qlraki47908h5c9mf1"300
TXT"google-site-verification=otgwTIY9F-b-FfbfbUI2VALTkgGcwyo7qhoj6vzSDIA"300
TXT"v=spf1 ip4:216.84.189.0/24 ip4:64.18.0.0/20 ip4:91.143.106.55 ip4:107.21.2.3 a:zgateway.zuora.com include:_spf.google.com include:mktomail.com include:_spf1.lynda.com include:linkedin.com ~all"300
TXT"wz2pkrghvpwld0jlvm13jqlqxqjtq6bn"300
CAA0 contactemail "caarecordaware@microsoft.com"3600

Checks

  • ✓ TTLs within range #32
    TTLs: A 1h, AAAA 1h, MX 5m, NS 1d. The NS TTL at the parent is 2d 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.
  • ✓ CAA restricts issuance #35
    Certificates may be issued by: .