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Plain-English guides to WHOIS, DNS, email authentication, TLS and blocklists, written for people who run domains.
Domains and registries
What a UK WHOIS record shows since GDPR
Why owner details are missing, what is still published, and how to read a .uk record today.
RDAP explained
The successor to WHOIS: what it is, why registries are switching, and what changes for you.
How to read a .co.uk registry record
IPS tags, data validation and status codes, explained field by field.
Domain status codes explained
What clientHold, pendingDelete, redemptionPeriod and the rest mean, and which ones need action.
Moving a .uk domain: IPS tags explained
How .uk transfers work, what an IPS tag is, and why a tag change is the whole transfer.
Lookalike domains and typosquatting
The variants people register to catch your traffic and your mail, how to find them, and what to do about each kind.
Finding subdomains through certificate logs
Why every HTTPS certificate is public, what that reveals about a domain, and how to use it to find forgotten hosts.
DNS
How DNS resolution works
From the root servers to your browser: the chain of lookups behind every page load.
DNS record types reference
A, AAAA, CNAME, MX, TXT, NS, SOA, CAA, SRV, DS, DNSKEY and HTTPS records: what each one does.
DNS propagation and TTLs
Why a change is visible in one place and not another, and how to plan changes so nobody notices.
DNSSEC explained
Signed zones, the chain of trust, and the two ways it breaks.
Subdomains and zone delegation
The difference between a record in your zone and a delegated zone, and why it matters for DNSSEC and consistency checks.
Email authentication and delivery
Writing an SPF record that works
The syntax, the ten-lookup limit, and the mistakes that quietly turn SPF off.
DKIM keys, selectors and rotation
How signing works, why the selector matters, and how to check a key is strong enough.
DMARC: from p=none to p=reject
A safe path from monitoring to enforcement without losing legitimate mail.
Why your email goes to spam: a diagnostic path
Work through authentication, reputation, infrastructure and content in the order receivers do.
Blocklists and how to get delisted
What DNS blocklists are, which ones matter, and the right order to fix a listing.
Reading email headers
Received lines, delays and Authentication-Results, and where to find the headers in Gmail and Outlook.
MTA-STS and TLS-RPT: forcing encrypted delivery
Why STARTTLS alone can be stripped, and how a small policy file and one DNS record close the gap.
BIMI: showing your logo in the inbox
What BIMI requires (a DMARC enforcement policy, an SVG and, for some providers, a certificate) and what it does not do.
Google and Yahoo bulk sender requirements
The checklist mailbox providers enforce for anyone sending in volume, and how to test each item.
Verifying an email address without sending to it
What a mail server will and will not tell you about a mailbox, and why "unknown" is often the honest answer.
Reading DMARC aggregate reports
What the daily XML reports from Google, Microsoft and Yahoo actually say, how to tell your own senders from spoofers, and when the numbers say you are ready to enforce.
Web and TLS
TLS certificates: chain, names and expiry
What a browser checks before it shows the padlock, and the findings whois.me.uk raises.
Redirects, www and the canonical host
Getting every variant of your address to one HTTPS URL without loops, chains or lost link value.
Security headers: what each one prevents
HSTS, CSP, X-Frame-Options, Referrer-Policy and friends, in the order they are worth adding.
AI crawlers, robots.txt and llms.txt
Which bots fetch your pages for AI, how to allow or block each one, and what the llms.txt convention is for.
Network and IP addresses
Looking for a specific finding code? See the fix guides.