SubNet mask types:
Class
Bits
IP SubNet
IP Broadcast
Mask (in decimal)
A
0
0.0.0.0
172.255.255.255
255.0.0.0
B
10
128.0.0.0
191.255.255.255
255.255.0.0
C
110
192.0.0.0
223.255.255.255
255.255.255.0
D
1110
224.0.0.0
239.255.255.255
not defined
E
1111
240.0.0.0
255.255.255.254
not defined
IP protocol uses IP addresses in order to identify the source and the destiny ina datagram.
But, the datagram travel inside a frame and it uses hardware addresses. By this reason, we
need to use ARP protocol, to determinate the hardware address corresponding to IP address
of the destinatary.The datagram is divided in two fields:
- Head: It has the information that the protocol needs to offer the service
- Data: It has the message itself. It must be delivered to destiny host.
The SubNet mask is a bits combination that is used to delimit the scope of a network. Its
function is to indicate to the devices which part of the IP address is the network number, including t
he subnet, and which part corresponds to the host.
Basically, with the SubNet mask (gateway, router, ...) will be able to know if needs to send data
inside or outside the network. For example, if the router has 192.168.1.1. as IP address and
255.255.255.0 as SubNet mask, all data sent to IP address which start in 192.168.1 will go to
local network and the rest for outside network (internet, etc.)
USER MANUAL
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