- How does IPv6 subnetting work and how does it differ from IPv4 subnetting? https://serverfault.com/questions/426183/how-does-ipv6-subnetting-work-and-how-does-it-differ-from-ipv4-subnetting
- http://engineering.chartbeat.com/2014/01/02/part-1-lessons-learned-tuning-tcp-and-nginx-in-ec2/
- http://veithen.github.io/2014/01/01/how-tcp-backlog-works-in-linux.html
why 10.0.0.0 IP address from let’s say 10.0.0.0/24 subnet is not used?
I of course know about explanation - “host zero isn’t used because it is the network number”, but why does it mean that we cannot use it?
so according to RFC1812 section 4.2.3.1:
(2) SHOULD silently discard on receipt (i.e., do not even deliver to
applications in the router) any packet addressed to 0.0.0.0 or {
<Network-prefix>, 0 }. If these packets are not silently
discarded, they MUST be treated as IP broadcasts (see Section
[5.3.5]). There MAY be a configuration option to allow receipt
of these packets. This option SHOULD default to discarding
them.
So 10.0.0.0 IP address from 10.0.0.0/24 subnet cannot be used because it will be discarded by the router 😄
10.0.0.0 is just for example here.
However, with RFC 3021, there was a change about /31s subnets for P2P links, that allow to use .0 addresses for P2P purposes:
(h) { , , 0 }
Subnetwork number. SHOULD NOT be used as a source address,
except when the originator is one of the endpoints of a point-
to-point link with a 31-bit mask. For other types of links, a
packet with such a destination SHOULD be silently discarded.
If these packets are not silently discarded, they MUST be treated
as IP broadcasts
- What is the network address (x.x.x.0) used for? https://serverfault.com/questions/135267/what-is-the-network-address-x-x-x-0-used-for