diff --git a/n/dns.md b/n/dns.md index f051b50..d7c627d 100644 --- a/n/dns.md +++ b/n/dns.md @@ -65,7 +65,23 @@ least temporary. Thus I think this list belongs here close enough. ## What is ECS? -EDNS Client-Subnet is a DNS extension letting the authoritative nameserver know your /24 or /56 (IPv6). /24 is the first three parts of your IPv4 address, /56 is 256 /64s and the recommendation to assign to you (although some ISPs just give you a /64). +EDNS Client-Subnet is a DNS extension letting the authoritative nameserver +know your `/24` (IPv4) or `/56` (IPv6). + +- /24 is the first three parts of your IPv4 address e.g. 192.0.2.xxx. + The last part of your IP address (the xxx) again is a number between 1 + to 254 (since 0 is reserved for the network itself and 255 is the + broadcast address). +- `/56` includes 256 `/64`s and if your ISP (Internet Service Provider) + follows [RFC 6177](https://datatracker.ietf.org/doc/html/rfc6177), + it's assigned solely to you meaning the authoritative nameserver will know + the request originated from your network. + - However many ISPs, especially wireless ones, + will just assign you a `64` which is required for + [stateless address autoconfiguration]() + which is the most common way of getting IPv6 address in your local area + network as opposed to IPv4 where you would have + [Dynamic Host Configuration Protocol (DHCP)](https://en.m.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol). ### Why to use ECS?