Guides
Beginner
Guides
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What is a port number?
If an IP address finds the server, the port finds the right program on it. The common ports, and how to see which ones…
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What is caching? Browser, page and object caches
Caching keeps a ready-made copy of something so it does not have to be built again. The layers that make websites fast, and when…
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How HTTPS works
What the padlock actually means, what a certificate proves, and what happens in the first fraction of a second of every secure connection.
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What is a CDN?
A content delivery network keeps copies of your site’s files in data centers around the world, so visitors download them from somewhere close.
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What is an IP address? IPv4 and IPv6 explained
The number every device on the internet uses to find every other device, the difference between IPv4 and IPv6, and public versus private addresses.
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How to set up SSH keys
Replace passwords with a key pair, log in without typing a password, and then switch password login off for good.
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How to connect to a server with SSH
Open a secure command line on a remote server from Windows, macOS or Linux, and understand the host key prompt you see the first…
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Website migration checklist
Everything to check before, during and after moving a website to a new host, so nothing is forgotten and nothing breaks.
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How to flush your DNS cache
Make your computer forget old DNS answers after a site move or record change. Commands for Windows, macOS, Linux and every major browser.
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What is a nameserver?
Nameservers hold your domain’s DNS records. Changing them moves control of every record to a new provider at once.