I am an Electrical Engineer learning about computer Networks, So this question might be childish and easy for most of you. Please answer it briefly. I am performing subnetting where I have this address 18.104.22.168. In this worksheet, I can understand all the data except a number of borrowed bits which are 4. Please tell me How and from where this 4 came from? I have downloaded different worksheets and docs but was not able to understand this.
The borrowed bits are the host bits in the default subnet mask that are used for network in the custom subnet mask.
In your example:
Last byte of the default subnet mask:
Binary Decimal 00000000 -> 0
Last byte of the custom subnet mask:
Binary Decimal 11110000 -> 240
The first four (4) bits go from host to network, they are borrowed bits.
It can be understood easily using CIDR notation:
Netmask CIDR Notation 255.255.255.255 32 Netmask CIDR Notation 255.255.255.0 24 Netmask CIDR Notation 255.255.255.240 28