1. Registration data
whois queries the registrar's database for who registered the domain, when it expires, and sometimes contact details.
whois example.comTyporithm · medium
WHOIS & DNS
whois-dns-osintosintwhoisdnsrecords
Saved on this device
Full lesson · 8 learning steps Open any exercise for focused practice
10%
Step 1 of 8 · intro card
Learn WHOIS & DNS
Domain & Infrastructure
WHOIS returns a domain's registration data and sometimes contacts; DNS records (A, MX, NS, TXT) map an organization's mail, services, and SPF/DKIM posture. Together they build the infrastructure picture from public data without touching the target.
WHOIS queries the registrar's records for a domain: who registered it, the registrar, creation and expiry dates, name servers, and — when privacy protection is off — contact emails and addresses.
DNS records expose the live infrastructure. A and AAAA records point to hosts, MX names the mail servers, NS lists the authoritative name servers, and TXT holds SPF, DKIM, and provider verification tokens.
Both queries hit public registries and resolvers, not the organization itself, so they are passive. Cross-referencing the two builds an infrastructure map from open data before any active probing.
01
whois reveals registration data and sometimes contacts.
02
MX and NS records show mail and name-server providers.
03
TXT records expose SPF/DKIM and SaaS verification tokens.
whois example.com
dig example.com ANY
dig +short MX example.com
host -t TXT example.comRead the implementation
Connect each part of the code to the concept before you type.
2. All records
dig ... ANY asks the resolver for every record type at once, sketching the domain's full DNS footprint.
dig example.com ANY3. Mail servers
MX records name the mail exchangers, revealing whether mail is self-hosted or sent through a provider like Google or Microsoft.
dig +short MX example.com4. TXT / SPF
TXT records hold SPF and DKIM policy and verification tokens, exposing the organization's email-security posture and the SaaS it uses.
host -t TXT example.comA complete learning loop
01
Understand
Read the concept map and follow the code breakdown.
02
Reconstruct
Type the implementation, repair mistakes and work through every recall exercise.
03
Verify
Use the final check without hints; revisit weak concepts in short practice sessions.