Practical explanations of how the internet actually works.
Which networks originate the most IPv4 space in Portugal, which AS numbers MEO, NOS, Vodafone and NOWO use, where they interconnect and how much of the routing is protected by RPKI.
Prefix, ASN, registration, RPKI, reverse DNS and location: what each line of an IP lookup means, and which of them are facts and which are estimates.
What websites see with a VPN on, how to check that it works, typical leaks, and what a VPN doesn't protect against.
IP address, headers, browser details and cookies: what is sent automatically, what needs your permission, and what you can limit.
Reverse DNS turns an IP address into a name. How the PTR record works, who controls it and why mail servers care.
Nothing loads, or only some sites do? A short, methodical check from your device to DNS.
No IPv6 address, IPv6 that exists but doesn't work, or sites that load slowly: a checklist from your device to your provider.
The protocol that ties networks together: prefixes, AS paths, how traffic finds its way, and why RPKI makes the internet safer.
Why a DNS change doesn't show everywhere at once, what TTL has to do with it, and how to plan a migration without downtime.
Why 255.255.255.0 and /24 are the same thing, how a mask separates network from host, and what wildcard masks are.
What your provider actually does, where it gets IP addresses, why a lookup may show another name than the brand you pay, and what it can see.
What an IP address really says about where you are, who can link it to you, and why 'IP tracing' in films is misleading.