Guides for your website, domain & email
Practical reading on DNS, domains, business email, authentication, and online security to help you manage your business services.
How Scammers Exploit Missing DMARC Records to Impersonate Any Domain
Without a DMARC policy, anyone can forge your From: address and send emails that look exactly like yours to your clients, employees, or partners. We break down how this works, real cases where it happened, and the exact DNS records you need to stop it.
Email Spoofing Explained: How Attackers Fake the From Address
The SMTP protocol has no built-in sender verification. Learn how phishing campaigns forge From headers, why inbox providers sometimes let them through, and the three records that close the gap: SPF, DKIM, and DMARC.
DNS Records Every Developer Must Know (A, MX, TXT, CNAME, PTR)
DNS is the phone book of the internet — but most developers only know about A records. This guide covers every record type that matters for email, web hosting, and security, with practical examples for each.
The 2016 DNC Hack: How a Broken DKIM Chain Helped Spread Disinformation
When DNC emails were leaked and published, DKIM signatures allowed anyone to verify their authenticity — or lack thereof. We analyze what the headers revealed, what was fabricated, and what proper email auth policies could have prevented.
DNS Cache Poisoning: How Attackers Redirect Your Traffic Without Breaking In
Cache poisoning lets an attacker inject fake DNS responses into a resolver's cache, silently redirecting users to malicious servers. We walk through the Kaminsky attack, how DNSSEC counters it, and what you can check on your own domain.
The DNS Audit Checklist: 10 Things to Verify Before You Launch a Domain
From MX records to DMARC policies to TTL values — here is the complete pre-launch DNS audit every domain owner should run. Includes the exact commands and tool links to verify each item in under 15 minutes.
SPF, DKIM, DMARC: What They Are, How They Work Together, and Why All Three Matter
Many domains have SPF but no DMARC. Many have DMARC set to p=none and think they are protected. This beginner-friendly guide explains the full authentication chain, what happens when one link is missing, and how to audit your own setup.
When Banks Get Spoofed: Analyzing the ING, Barclays, and PayPal DMARC Gaps
Major financial institutions were caught with p=none DMARC policies for years — meaning any attacker could send mail as their domains. We document the timeline, the phishing campaigns that exploited it, and how each bank eventually fixed it.
Subdomain Takeover via Dangling DNS: The Silent Threat Hiding in Your Zone
When a CNAME record points to a cloud service that no longer exists, an attacker can register that service and take over your subdomain. This vulnerability has affected Microsoft, Shopify, HubSpot, and thousands of other organizations.
Understanding DNS TTL: Why a Wrong Value Can Lock You Out for 48 Hours
TTL (Time to Live) controls how long DNS responses are cached by resolvers worldwide. Set it too high before a migration and your change can take days to propagate. Set it too low and you hammer your DNS server. Here is how to get it right.
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