Where and why is the subnet mask used starting from bit 25?

Question

Computer networks

What is the subnet mask used for, say 26, 30

Answer 1

For small networks, which is logical. for example, if you have 10 employees in your department, then giving a subnet of 24-25 is somehow redundant.
30 is well suited for connecting some devices, for example, to connect two routers.
32 for a device label, for example in OSPF device id is an ip address, you can create an addressing that would describe your routing processes without sitting on the data network.

Answer 2

Point-to-point VPNs have a /31 network - just for two devices, the failover network is also the same.
We will also give an example of networks not for employees, the architecture of any services should be two or three levels, that is, DMZ + APP + DB or DMZ + MZ (APP + DB). From here we get that if you have hundreds of services in your company and all of them have few servers, then it makes no sense to allocate large networks if the service never has so many servers. It is also convenient when, for example, we give a set of networks 192.168.1.x to one service, another 192.168.2.x - so we visually remember whose set of networks it is according to the third act. Also, for greater security, you place hypervisor interfaces in a separate segment, cryptoservers and HSM in another, server management interfaces (iLo) in another, development, test, demo servers are also in separate ones. For example, we already have ~ 2000 networks in our company,