Guides
How DNS, nameservers, DNSSEC, SSL certificates and email authentication actually work, and how to troubleshoot them. Each guide links to the tool that checks what it describes.
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DNS Record Types Explained: A, CNAME, MX, TXT & More
The ten record types you will meet most often, what each one is for, and how they go wrong.
9 min read
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DNSSEC Validation Failed? Fix DS Mismatch & SERVFAIL
Stale DS records, provider migrations, expired signatures and the other ways DNSSEC breaks.
9 min read
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How Long Does DNS Propagation Take? Why It Varies
TTLs, negative caching and the real reasons "propagation" seems random—with timings per change.
8 min read
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Fix SSL Certificate Errors: NET::ERR_CERT Codes
Name mismatches, missing intermediates, self-signed certificates and handshake failures, by error code.
9 min read
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SPF, DKIM and DMARC Explained (Gmail & Yahoo Rules)
The three records that prove your mail is really from you, and how receivers combine them.
9 min read
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Why Are My Emails Going to Spam? How to Find and Fix It
The two checks that explain most spam-folder mail: blacklists and authentication, and how to fix each.
7 min read
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Nameserver Mismatch: Registrar vs Zone NS Records
Registrar vs. zone NS records, lame servers and how to clean up after a provider move.
7 min read