Guides
What we wish we'd read first
Guides written for web agencies and freelancers, not for system administrators. Each one carries the matching free tool: you read, then check your own domain without leaving the page.
8 min read
SPF, DKIM and DMARC: the guide for web agencies
Three DNS records, half an hour of work, and two problems solved at once: your clients stop landing in spam, and nobody can write in their name any more. Here is how to set them up, in the right order, without breaking anything.
Read the guide7 min read
Monitoring your clients' domains without losing your days to it
You delivered the site, you handed over the credentials, and the domain is still your problem. Here is how to set up monitoring that holds — the inventory, what to watch, how often, and who should be told.
Read the guide6 min read
The 7 checks to run before delivering a site
The short list of what we look at before sending the delivery email. None of these seven points needs any special access, and each of them has already cost someone a weekend.
Read the guide
Reference guides
One record per page: what it is, how to read it, and the table you keep open beside you.
8 min read
What is an SPF record?
SPF: the list of servers allowed to send mail as your domain7 min read
What is DKIM?
DKIM: the signature that travels with the message8 min read
What is DMARC?
DMARC: the rule that says what to do whenSPFandDKIMfail7 min read
What is DNSSEC?
DNSSEC: signed DNS answers, and what it costs when they break7 min read
What is a CAA record?
CAA: the list of authorities allowed to issue your certificates
7 min read
What is the TTL of a DNS record?
TTL: how long a DNS answer stays in cache7 min read
What are A and AAAA records?
A and
AAAA: the two ways of saying where a name lives8 min read
What is a CNAME record?
CNAME: the DNS alias, and the four things it cannot do8 min read
What is an MX record?
MX: where a domain's mail goes, and in what order7 min read
What are WHOIS and RDAP?
WHOIS and
RDAP: reading a domain's registration record7 min read
What is a certificate chain?
The certificate chain: three links, and the one people forget
8 min read
What is HSTS?
HSTS: forcing HTTPS, and the trap on the way back