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Short, precise explanations of addresses, networks and the registrations around them.
What is an IP address?
The number your connection is reachable at — and what can be read from it.
IPv4 and IPv6: the difference
Why there are two kinds of address, and why you probably have both.
Public and private IP addresses
The difference between the address your router gives you and the address the world sees.
What is an ASN?
The number behind the network that announces your traffic on the internet.
What is DNS?
How a domain name becomes an address, and which records are involved.
What is reverse DNS?
From address to name — and why mail servers pay attention to it.
WHOIS and RDAP
Who registered a domain or IP range — and why that says less than people assume.
CIDR and subnets
What the number after the slash means, and what you calculate with it.