quizlet.com

Checked 22 October 2026, 10:24 UTC · via 8.8.8.8
✗Problems found
23 passed 3 warnings 1 failed 7 info

Registration

info

.com generic · GoDaddy.com, LLC · expires 2029-07-15

Found

TLD
.com (generic)
ICANN policies apply
yes
Registrar
GoDaddy.com, LLC
Registered
15 July 2004
Last changed
16 July 2026
Expires
15 July 2029
Status
client delete prohibited, client renew prohibited, client transfer prohibited, client update prohibited
Registry nameservers
cns1.quizlet.com, cns2.quizlet.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 2029-07-15 #3
    The registration is valid until 2029-07-15 (997 days).
  • ✓ Transfer locked #4
    Registry status: client delete prohibited, client renew 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

cns1.quizlet.com, cns2.quizlet.com

Found

Parent zone
com
Delegation from
a.gtld-servers.net (192.5.6.30)
NS at the parent
cns1.quizlet.com, cns2.quizlet.com
NS in the zone
ian.ns.cloudflare.com, lily.ns.cloudflare.com
NameserverAddressesNetwork (AS)Glue
cns1.quizlet.com (parent only)104.16.133.27 104.16.134.27AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US173.245.58.37
cns2.quizlet.com (parent only)104.16.133.27 104.16.134.27AS13335 CLOUDFLARENET - Cloudflare, Inc., US AS13335 CLOUDFLARENET - Cloudflare, Inc., US173.245.59.32
ian.ns.cloudflare.com (zone only)172.64.33.118 108.162.193.118 173.245.59.118 2606:4700:58::adf5:3b76 2803:f800:50::6ca2:c176 2a06:98c1:50::ac40:2176AS13335 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., US-
lily.ns.cloudflare.com (zone only)108.162.192.130 173.245.58.130 172.64.32.130 2803:f800:50::6ca2:c082 2606:4700:50::adf5:3a82 2a06:98c1:50::ac40:2082AS13335 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., US-

Checks

  • i
    2 nameservers
    Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: cns1.quizlet.com, cns2.quizlet.com.
    #6
  • !
    NS sets differ
    The nameservers at the parent and in the zone should be the same. Only at the parent: cns1.quizlet.com, cns2.quizlet.com; only in the zone: ian.ns.cloudflare.com, lily.ns.cloudflare.com. ian.ns.cloudflare.com, lily.ns.cloudflare.com report NS ian.ns.cloudflare.com lily.ns.cloudflare.com.
    #7
  • !
    Glue differs from the zone
    The addresses at the parent (glue) differ from the addresses in the zone: cns1.quizlet.com (glue 173.245.58.37, zone 104.16.133.27, 104.16.134.27); cns2.quizlet.com (glue 173.245.59.32, zone 104.16.133.27, 104.16.134.27). Update the glue at your registrar.
    #8
  • ✓ 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 8 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): 16 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: cns1.quizlet.com, cns2.quizlet.com.
    #13

Nameservers

fail

12 of 16 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
cns1.quizlet.com 104.16.133.27no responsenono / no--
cns1.quizlet.com 104.16.134.27no responsenono / no--
cns2.quizlet.com 104.16.133.27no responsenono / no--
cns2.quizlet.com 104.16.134.27no responsenono / no--
ian.ns.cloudflare.com 172.64.33.118NOERROR, 4 ms, authoritativenoyes / yesrefused2026.10.2
ian.ns.cloudflare.com 108.162.193.118NOERROR, 4 ms, authoritativenoyes / yesrefused2026.10.2
ian.ns.cloudflare.com 173.245.59.118NOERROR, 4 ms, authoritativenoyes / yesrefused2026.10.2
ian.ns.cloudflare.com 2606:4700:58::adf5:3b76NOERROR, 8 ms, authoritativenoyes / yesrefused2026.10.2
ian.ns.cloudflare.com 2803:f800:50::6ca2:c176NOERROR, 8 ms, authoritativenoyes / yesrefused2026.10.2
ian.ns.cloudflare.com 2a06:98c1:50::ac40:2176NOERROR, 8 ms, authoritativenoyes / yesrefused2026.10.2
lily.ns.cloudflare.com 108.162.192.130NOERROR, 4 ms, authoritativenoyes / yesrefused2026.10.2
lily.ns.cloudflare.com 173.245.58.130NOERROR, 4 ms, authoritativenoyes / yesrefused2026.10.2
lily.ns.cloudflare.com 172.64.32.130NOERROR, 4 ms, authoritativenoyes / yesrefused2026.10.2
lily.ns.cloudflare.com 2803:f800:50::6ca2:c082NOERROR, 5 ms, authoritativenoyes / yesrefused2026.10.2
lily.ns.cloudflare.com 2606:4700:50::adf5:3a82NOERROR, 5 ms, authoritativenoyes / yesrefused2026.10.2
lily.ns.cloudflare.com 2a06:98c1:50::ac40:2082NOERROR, 5 ms, authoritativenoyes / yesrefused2026.10.2

Checks

  • ✗
    Nameservers not responding
    These addresses did not answer, so resolvers waste time on timeouts: cns1.quizlet.com (104.16.133.27): read udp 46.225.38.91:44457->104.16.133.27:53: i/o timeout; cns1.quizlet.com (104.16.134.27): read udp 46.225.38.91:34303->104.16.134.27:53: i/o timeout; cns2.quizlet.com (104.16.133.27): read udp 46.225.38.91:47825->104.16.133.27:53: i/o timeout; cns2.quizlet.com (104.16.134.27): read udp 46.225.38.91:54708->104.16.134.27:53: 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.
  • !
    Software version disclosed
    These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: ian.ns.cloudflare.com: "2026.10.2"; lily.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 2417572867 · primary ian.ns.cloudflare.com

Found

Primary (MNAME)
ian.ns.cloudflare.com
Contact (RNAME)
dns.cloudflare.com
Serial
2417572867
Refresh / retry
10000 s / 2400 s
Expire
604800 s
Negative TTL
1800 s

Serial per nameserver

NameserverSerial
ian.ns.cloudflare.com (172.64.33.118)2417572867
ian.ns.cloudflare.com (108.162.193.118)2417572867
ian.ns.cloudflare.com (173.245.59.118)2417572867
ian.ns.cloudflare.com (2606:4700:58::adf5:3b76)2417572867
ian.ns.cloudflare.com (2803:f800:50::6ca2:c176)2417572867
ian.ns.cloudflare.com (2a06:98c1:50::ac40:2176)2417572867
lily.ns.cloudflare.com (108.162.192.130)2417572867
lily.ns.cloudflare.com (173.245.58.130)2417572867
lily.ns.cloudflare.com (172.64.32.130)2417572867
lily.ns.cloudflare.com (2803:f800:50::6ca2:c082)2417572867
lily.ns.cloudflare.com (2606:4700:50::adf5:3a82)2417572867
lily.ns.cloudflare.com (2a06:98c1:50::ac40:2082)2417572867

Checks

  • ✓ Serial 2417572867 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 ian.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 2417572867 is a Unix timestamp (2046-08-11 04:01 UTC).

DNSSEC

pass

Signed, DS published at parent

Found

Validated by resolver
yes
Signatures valid until
23 October 2026

DS at the parent

Key tagAlgorithmDigestMatches a key
2371ECDSAP256SHA256 (13)SHA256 F88D6ACE68619E82…yes

DNSKEY in the zone

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

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 2371 (SHA256).
  • ✓ 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 09:24 UTC and expires at 2026-10-23 11:24 UTC.

Records

info

38 records at the apex

Found

Read from
172.64.33.118:53
TypeValueTTL
SOAian.ns.cloudflare.com. dns.cloudflare.com. 2417572867 10000 2400 604800 18001800
NSian.ns.cloudflare.com.86400
NSlily.ns.cloudflare.com.86400
A104.16.133.27300
A104.16.134.27300
MX10 aspmx.l.google.com.300
MX20 alt1.aspmx.l.google.com.300
MX30 alt2.aspmx.l.google.com.300
MX40 aspmx2.googlemail.com.300
MX50 aspmx3.googlemail.com.300
MX60 aspmx4.googlemail.com.300
MX70 aspmx5.googlemail.com.300
TXT"24F3373645"300
TXT"6bc7fbl8y9h6lng2n9mfymp16dy63g5s"300
TXT"762642896-4167472"300
TXT"K6b3CtLBfcqpRDNJfg7WcyP9qg"300
TXT"MS=ms29141506"300
TXT"PAEZFEC4AVFC77KOVF1R0H57BRTMST936SZT1YXT"300
TXT"_c6ifay1uuzwpf3c6q917aojjdd6p1ea"300
TXT"anthropic-domain-verification-c3qp9g=07K3uDxfCV06dDvwrJXNZeulX"300
TXT"apple-domain-verification=GhqRH5BdB8mVkDUq"300
TXT"atlassian-domain-verification=RY6sTRPfyrQlcq2vgiA3xPplUkOM9JLXJSDEQotm9vlyY86HuuDBGaGDyLm9oTNF"300
TXT"atlassian-domain-verification=plVFZkxuXPVmwzDvcpY5wv9jzzqQtxQtByhFAEdY+P7nj9p8snaZ075RZ/N1leeb"300
TXT"cursor-domain-verification-nvvmrz=MJvAnXKyNFtJKJABZah0XyVgc"300
TXT"docusign=a6f2c83c-9542-4ba7-92e3-032b45a00375"300
TXT"facebook-domain-verification=pzag31nnjljvy81xhps4rggqtj46rq"300
TXT"google-site-verification=5qTpwRH3290N26h2y-Dt-SOmOyX8xLramCneO4W9nDs"300
TXT"google-site-verification=W5dcXTOxPUzVvjBMgdJzZSMSebqrWo0O6CBV0FN1dhY"300
TXT"google-site-verification=w1N3KNUCtJ6ovW-SihpCFUCwQqB_mC7HMMn2FDeig48"300
TXT"google-site-verification=zwWiKvbXdW7mObtno1aea-OcQHXpmaZ2CvcW3qclYnA"300
TXT"hcp-domain-verification=0610f95c7b0e248dd930b7076e658fa93c1a08ccfa5f91e96b612919e6ef5807"300
TXT"linear-domain-verification=c63cnkxcepz3"300
TXT"onetrust-domain-verification=31c369ac7a3544d19c07ea059d09b5f3"300
TXT"onetrust-domain-verification=7316088ca8db44f78ca82d9e961f6442"300
TXT"openai-domain-verification=dv-5Nx1YJVH5ae1OqCzL1NiNOu0"300
TXT"pinterest-site-verification=ea81483d36f8c1be6f86693a81004261"300
TXT"v=spf1 include:spf.mtasv.net include:_spf.google.com include:sendgrid.net include:mail.zendesk.com include:_spf.salesforce.com ~all"300
TXT"verification_token=hwfem4LxsGXoCR8htJxKqQI2W"300

Checks

  • ✓ TTLs within range #32
    TTLs: A 5m, 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.
  • 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
  • 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