Knowledge: Domain, DNS, Email and SEO

Hands-on tutorials for everything IP Beacon checks. From DNSBL listings to SPF/DMARC, all the way to SEO standards like llms.txt and security.txt. With examples, Wikipedia links, and direct tests.

DNSBL & spam reputation

How spam blocklists work and how to get off them if you are listed.

Spamhaus PBL: what it is and how to get off it

The Spamhaus Policy Block List intentionally lists all dynamic IPs (DSL, cable, mobile). If you want to send mail legitimately, you need a different setup — or to apply for delisting.

⏱ 5 min

Domain verification

How to bind Google, Bing, Microsoft 365 and other services to your domain.

Understanding WHOIS and RDAP — where domain data actually comes from

WHOIS has been around since 1982 — RDAP is its modern successor since 2015. How registration and expiry data are queried, and why some domains expose less data.

⏱ 6 min

Verify Bing Webmaster Tools via CNAME — the robust way

Bing offers three verification methods — meta tag, XML file, CNAME. The CNAME route is most robust because it survives theme and plugin updates.

⏱ 4 min

Verifying Google Search Console — all 5 methods compared

Google Search Console is the most important webmaster tool — free, with crawl data, indexing status, search query statistics. First you must verify the domain.

⏱ 5 min

Email authentication

SPF, DMARC, DKIM, DANE and MTA-STS — the foundations of deliverable email.

Creating an SPF record — the entry point to clean email delivery

SPF tells receiving mail servers which IPs are allowed to send mail for your domain. Without SPF, your emails land in spam more often. Step-by-step guide with examples.

⏱ 6 min

DANE/TLSA — pinning TLS certificates in DNS

DANE pins TLS certificates in DNS, making them independent of the CA system. Especially valuable for email — with DNSSEC, effective protection against MITM.

⏱ 6 min

DKIM setup — cryptographic signature for your mail

DKIM is the cryptographic signature that proves each of your messages really came from your domain. Complete guide with key generation, DNS setup, and testing.

⏱ 6 min

DMARC setup — from p=none to p=reject

DMARC is the policy layer on top of SPF and DKIM. It tells receivers what to do when authentication fails, plus delivers daily reports.

⏱ 7 min

Feedback Loops — when recipients send spam clicks back to you

When a Gmail user marks your mail as spam, Gmail knows. But who tells you, the sender? Feedback Loops (FBLs) do — the major programs from Google, Yahoo, Microsoft, AOL, and Apple.

⏱ 7 min

MTA-STS and TLS-RPT — enforcing TLS for mail transport

STARTTLS for SMTP is optional and therefore attackable. MTA-STS enforces TLS encryption for mail transport, TLS-RPT delivers reports about problems.

⏱ 5 min

Whitelisting and the Certified Sender Alliance — the direct route to the inbox

Spam filters are one thing — whitelisting is the opposite. How the Certified Sender Alliance (CSA), Spamhaus DWL, and Validity Sender Score work, and which program is worth it for whom.

⏱ 7 min

Web security

HSTS, CSP and security.txt — what browsers and security researchers expect.

Enabling HSTS — the browser contract for HTTPS-only

HSTS forces browsers to only access your domain over HTTPS — even if the user types "http://". Protection against downgrade attacks with minimal effort.

⏱ 5 min

Setting up security.txt — the RFC 9116 standard for vulnerability reports

security.txt tells security researchers how to report vulnerabilities. Standardized as RFC 9116, simple to set up, practically useful.

⏱ 4 min

SEO & discoverability

robots.txt, sitemap.xml, canonical links, llms.txt — what search engines and AI crawlers expect.

Canonical link element — avoiding duplicate content

The canonical link tells search engines which URL is the "real" version of a page. Important for tracking params, language variants, print versions.

⏱ 5 min

Embed the reputation badge on your own website

A reputation badge in your footer shows visitors at a glance that your domain is externally monitored and healthy. How to enable, embed, and style it.

⏱ 4 min

Open Graph meta tags — how your page looks on social media

Open Graph controls the preview image and text when your page is shared on Facebook, LinkedIn, WhatsApp, Slack or iMessage. Complete tag set with best practices.

⏱ 5 min

Title tag and meta description — the classics, done right

Title and meta description are the oldest SEO levers — and still the most effective for click rates. Lengths, tone, keywords, and common mistakes.

⏱ 5 min

Understanding the Reputation Score — how A+/F really works

A single score 0–100 for your domain's health sounds simple — the factors behind it are not. What DNSBL, SSL status, SPF config, domain age, and uptime have in common, and how they combine into a grade.

⏱ 7 min

llms.txt — the new standard for AI crawlers

Since 2024, ChatGPT, Claude, Perplexity and other AI systems use an llms.txt file for structured access to your content. What goes in, how it differs from robots.txt.

⏱ 5 min

robots.txt — what crawlers may do and what not

robots.txt has steered crawler behaviour since 1994. Classic rules, modern AI-crawler extensions, common mistakes, and a complete example.

⏱ 5 min

sitemap.xml — structured URL overview for crawlers

A sitemap is the official list of all URLs on your site — crawlers use it for complete indexing and prioritization. Here's how to build a valid one.

⏱ 5 min