Summary
- Registrar
- NameCheap, Inc.
- Status
- clientTransferProhibited
- Created on
- June 7, 2013
- Expires on
- June 7, 2027
- Name servers
- ns3.linode.com, ns2.linode.com, ns1.linode.com, ns5.linode.com, ns4.linode.com
- Mail servers
- —
- DKIM
- No key found among the common selectors
- Website
- See the website
MX, SPF, DKIM and DMARC: the e-mail records
Four DNS records make a domain's e-mail work. MX says where e-mails sent to dthompson.us arrive; SPF, DKIM and DMARC let mail servers check that an e-mail claiming to come from dthompson.us was really sent by this domain, which protects it against spoofing.
MX
An MX (Mail Exchanger) record designates a server that receives e-mails sent to the domain. When someone writes to an @dthompson.us address, their mail server queries the DNS for the domain's MX records, then delivers the message to the server they point to.
Example record
dthompson.us MX 10 mx1.dthompson.us. dthompson.us MX 20 mx2.dthompson.us.
What the record contains
- 10, 20
- Priority: the server with the lowest number is tried first. Servers with equal priority share the load.
- mx1.dthompson.us.
- Host name of the mail server. It must point to an A or AAAA record: an IP address or an alias (CNAME) is not allowed here.
- 0 .
- An MX "0 .", called a null MX, declares that the domain accepts no e-mail: sending servers give up at once instead of retrying.
Declaring at least two servers with different priorities avoids losing e-mails during an outage: sending servers retry for several days and fall back on the backup server. Without any MX, they try to deliver directly to the IP address of the domain.
SPF
SPF (Sender Policy Framework) is a TXT record listing the servers allowed to send e-mails on behalf of the domain. The receiving server checks that the sender is on this list. The final "all" rule says what to do with other servers: reject them (-all), flag their e-mails as suspicious (~all) or make no decision (?all).
Example record
dthompson.us TXT "v=spf1 mx include:_spf.google.com ip4:192.0.2.10 -all"
What the record contains
- v=spf1
- Identifies the record as an SPF policy. It must come first.
- ip4, ip6
- Allows a specific IP address or an address range, for example ip4:192.0.2.0/24.
- a, mx
- Allows the addresses of the domain itself (A record) or those of its mail servers (MX).
- include
- Allows the servers of another domain, usually a sending service: include:_spf.google.com for Google Workspace.
- -all, ~all
- Final rule, applied to every other server. Its qualifier decides what happens to them: - rejects them, ~ flags their e-mails as suspicious, ? makes no decision, + accepts them (avoid it).
A domain must publish only one SPF record, and its evaluation cannot exceed 10 DNS lookups (include, a, mx, exists, redirect). Beyond that, mail servers treat it as invalid.
DKIM
DKIM (DomainKeys Identified Mail) signs every outgoing e-mail with a private key. The matching public key is published in a TXT record at selector._domainkey.dthompson.us, so the recipient can check that the message really comes from the domain and was not altered on the way. The selector is chosen by each sending service and cannot be guessed: Dataweaz checks the most common ones (Google Workspace, Microsoft 365, Mailchimp, SendGrid…), so a key published under another selector may exist without appearing here.
Example record
google._domainkey.dthompson.us TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA…"
What the record contains
- v=DKIM1
- Protocol version. Optional but recommended, in which case it must come first.
- k
- Key algorithm: rsa, the most common, or ed25519.
- p
- Public key, base64-encoded. An empty value means the key has been revoked.
- t
- Flags: y marks a key in testing, whose failures must not be penalized; s forbids its use for subdomains.
Each sending service publishes its key under its own selector (google, selector1, k1…), which allows several keys and seamless rotation. A 2048-bit RSA key is recommended today.
DMARC
DMARC (Domain-based Message Authentication, Reporting and Conformance) builds on SPF and DKIM. Published on _dmarc.dthompson.us, it tells mail servers what to do with an e-mail that fails these checks (let it through, send it to spam or reject it) and where to send reports.
Example record
_dmarc.dthompson.us TXT "v=DMARC1; p=quarantine; rua=mailto:[email protected]; adkim=r; aspf=r"
What the record contains
- v=DMARC1
- Identifies the record as a DMARC policy. It must come first.
- p
- Policy applied to e-mails that fail the checks: none (monitoring only), quarantine (spam folder) or reject.
- sp
- Subdomain policy. Without it, subdomains follow the domain's policy.
- rua
- Address that receives daily aggregate reports about e-mails sent on behalf of the domain, whether they pass the checks or not.
- ruf
- Address that receives detailed failure reports, message by message. Few providers still send them.
- pct
- Percentage of e-mails subject to the policy, for a gradual rollout. 100 by default.
- adkim, aspf
- DKIM and SPF alignment: r (relaxed, a subdomain of the same domain is enough) or s (strict, the domain must be identical).
To roll out DMARC without blocking legitimate e-mails, start with p=none and an rua address, analyze the reports to find every service sending on behalf of the domain, then move to quarantine and finally to reject.
DNS records of dthompson.us
IP addresses (A and AAAA)
An A record maps the domain name to an IPv4 address: the address of the server that browsers contact to display the website. The AAAA record does the same for an IPv6 address. A domain can have several of them to spread visits across several servers.
| Type | IP address |
|---|---|
| A | 45.79.131.136 |
| AAAA | 2600:3c03::2000:ebff:fe5a:8d42 |
Name servers (NS)
NS records designate the authoritative DNS servers of the domain: they answer every question about its other records (A, MX, TXT…). They are provided by the registrar, the hosting provider or a dedicated DNS service, and several servers are declared so that the domain keeps working if one of them fails.
| Server | IP address |
|---|---|
| ns3.linode.com | 92.123.95.3 |
| ns2.linode.com | 92.123.94.3 |
| ns1.linode.com | 92.123.94.2 |
| ns5.linode.com | 92.123.95.2 |
| ns4.linode.com | 92.123.95.4 |
Mail servers (MX)
MX records point to the servers that receive e-mails sent to the domain, that is to @dthompson.us addresses. Each server has a priority: the one with the lowest number is tried first, the others take over if it fails. Without an MX record, the domain cannot receive e-mails.
No mail server: the domain does not receive e-mails.
TXT records
TXT records hold free text. They are used to prove ownership of the domain to online services (Google, Microsoft, Facebook…) and to publish e-mail security rules: SPF on the domain itself, DMARC on _dmarc.dthompson.us.
No TXT record.
Related IP addresses
IPv4 addresses used by dthompson.us: website, name servers, mail servers and senders authorized by SPF.
| IP address | Used for | /24 block |
|---|---|---|
| 45.79.131.136 | Website | 45.79.131.0/24 |
| 92.123.95.3 | Name server ns3.linode.com | 92.123.95.0/24 |
| 92.123.94.3 | Name server ns2.linode.com | 92.123.94.0/24 |
| 92.123.94.2 | Name server ns1.linode.com | 92.123.94.0/24 |
| 92.123.95.2 | Name server ns5.linode.com | 92.123.95.0/24 |
| 92.123.95.4 | Name server ns4.linode.com | 92.123.95.0/24 |
WHOIS of the domain dthompson.us
Domain Name: dthompson.us Registry Domain ID: D40696757-US Registrar WHOIS Server: whois.namecheap.com Registrar URL: http://www.namecheap.com Updated Date: 2026-09-29T00:11:13Z Creation Date: 2013-06-07T13:43:05Z Registry Expiry Date: 2027-06-06T23:59:59Z Registrar: NameCheap, Inc. Registrar IANA ID: 1068 Registrar Abuse Contact Email: [email protected] Registrar Abuse Contact Phone: +1.6613102107 Domain Status: clientTransferProhibited https://icann.org/epp#clientTransferProhibited Registry Registrant ID: C5A61566D9E41443E9EF60B3A2A75D3BF-GDREG Registrant Name: David Thompson Registrant Organization: Registrant Street: 111 Town Farm Road Registrant Street: Registrant Street: Registrant City: Brookfield Registrant State/Province: MA Registrant Postal Code: 01506 Registrant Country: US Registrant Phone: +1.7742896629 Registrant Phone Ext: Registrant Fax: Registrant Fax Ext: Registrant Email: [email protected] Registrant Application Purpose: P3 Registrant Nexus Category: C11 Registry Admin ID: C490859D9ECE544B3BA5D468F1FD39EF3-GDREG Admin Name: David Thompson Admin Organization: Admin Street: 111 Town Farm Road Admin Street: Admin Street: Admin City: Brookfield Admin State/Province: MA Admin Postal Code: 01506 Admin Country: US Admin Phone: +1.7742896629 Admin Phone Ext: Admin Fax: Admin Fax Ext: Admin Email: [email protected] Admin Application Purpose: P3 Admin Nexus Category: C11 Registry Tech ID: CDCF49AB1DDB044EB991DD11088B21A37-GDREG Tech Name: David Thompson Tech Organization: Tech Street: 111 Town Farm Road Tech Street: Tech Street: Tech City: Brookfield Tech State/Province: MA Tech Postal Code: 01506 Tech Country: US Tech Phone: +1.7742896629 Tech Phone Ext: Tech Fax: Tech Fax Ext: Tech Email: [email protected] Tech Application Purpose: P3 Tech Nexus Category: C11 Name Server: ns1.linode.com Name Server: ns2.linode.com Name Server: ns3.linode.com Name Server: ns4.linode.com Name Server: ns5.linode.com DNSSEC: unsigned URL of the ICANN Whois Inaccuracy Complaint Form: https://www.icann.org/wicf/ >>> Last update of WHOIS database: 2026-10-01T21:05:32Z <<< For more information on Whois status codes, please visit https://icann.org/epp .US WHOIS Complaint Tool - http://www.whoiscomplaints.us Advanced WHOIS Instructions - http://whois.us/help.html Registry Services, LLC, the Registry Administrator for .US, has collected this information for the WHOIS database through a .US-Accredited Registrar. This information is provided to you for informational purposes only and is designed to assist persons in determining contents of a domain name registration record in the registry database. Registry Services, LLC makes this information available to you "as is" and does not guarantee its accuracy. By submitting a WHOIS query, you agree that you will use this data only for lawful purposes and that, under no circumstances will you use this data: (1) to allow, enable, or otherwise support the transmission of mass unsolicited, commercial advertising or solicitations via direct mail, electronic mail, or by telephone; (2) in contravention of any applicable data and privacy protection laws; or (3) to enable high volume, automated, electronic processes that apply to the registry (or its systems). Compilation, repackaging, dissemination, or other use of the WHOIS database in its entirety, or of a substantial portion thereof, is not allowed without our prior written permission. We reserve the right to modify or change these conditions at any time without prior or subsequent notification of any kind. By executing this query, in any manner whatsoever, you agree to abide by these terms. NOTE: FAILURE TO LOCATE A RECORD IN THE WHOIS DATABASE IS NOT INDICATIVE OF THE AVAILABILITY OF A DOMAIN NAME. All domain names are subject to certain additional domain name registration rules. For details, please visit our site at www.whois.us. Domain name: dthompson.us Registry Domain ID: D40696757-US Registrar WHOIS Server: whois.namecheap.com Registrar URL: http://www.namecheap.com Updated Date: 2026-06-04T13:33:52.01Z Creation Date: 2013-06-07T13:43:05.00Z Registrar Registration Expiration Date: 2027-06-06T23:59:59.00Z Registrar: NAMECHEAP INC Registrar IANA ID: 1068 Registrar Abuse Contact Email: [email protected] Registrar Abuse Contact Phone: +1.9854014545 Reseller: NAMECHEAP INC Domain Status: clientTransferProhibited https://icann.org/epp#clientTransferProhibited Registry Registrant ID: Redacted for Privacy Purposes Registrant Name: Redacted for Privacy Purposes Registrant Organization: Redacted for Privacy Purposes Registrant Street: Redacted for Privacy Purposes Registrant City: Redacted for Privacy Purposes Registrant State/Province: MA Registrant Postal Code: Redacted for Privacy Purposes Registrant Country: US Registrant Phone: Redacted for Privacy Purposes Registrant Phone Ext: Redacted for Privacy Purposes Registrant Fax: Redacted for Privacy Purposes Registrant Fax Ext: Redacted for Privacy Purposes Registrant Email: Select Contact Domain Holder link at https://www.namecheap.com/domains/whois/result?domain=dthompson.us&contactForm=1 Registry Admin ID: Redacted for Privacy Purposes Admin Name: Redacted for Privacy Purposes Admin Organization: Redacted for Privacy Purposes Admin Street: Redacted for Privacy Purposes Admin City: Redacted for Privacy Purposes Admin State/Province: Redacted for Privacy Purposes Admin Postal Code: Redacted for Privacy Purposes Admin Country: Redacted for Privacy Purposes Admin Phone: Redacted for Privacy Purposes Admin Phone Ext: Redacted for Privacy Purposes Admin Fax: Redacted for Privacy Purposes Admin Fax Ext: Redacted for Privacy Purposes Admin Email: Select Contact Domain Holder link at https://www.namecheap.com/domains/whois/result?domain=dthompson.us&contactForm=1 Registry Tech ID: Redacted for Privacy Purposes Tech Name: Redacted for Privacy Purposes Tech Organization: Redacted for Privacy Purposes Tech Street: Redacted for Privacy Purposes Tech City: Redacted for Privacy Purposes Tech State/Province: Redacted for Privacy Purposes Tech Postal Code: Redacted for Privacy Purposes Tech Country: Redacted for Privacy Purposes Tech Phone: Redacted for Privacy Purposes Tech Phone Ext: Redacted for Privacy Purposes Tech Fax: Redacted for Privacy Purposes Tech Fax Ext: Redacted for Privacy Purposes Tech Email: Select Contact Domain Holder link at https://www.namecheap.com/domains/whois/result?domain=dthompson.us&contactForm=1 Name Server: ns1.linode.com Name Server: ns2.linode.com Name Server: ns3.linode.com Name Server: ns4.linode.com Name Server: ns5.linode.com DNSSEC: unsigned URL of the ICANN WHOIS Data Problem Reporting System: http://wdprs.internic.net/ >>> Last update of WHOIS database: 2026-10-01T14:05:33.54Z <<< For more information on Whois status codes, please visit https://icann.org/epp % Query time: 1239 msec % WHEN: Thu Oct 01 21:05:32 UTC 2026