Internet Protocol (IP)
A device's "phone number" or "street address."
NETWORKING
1/12/20251 min read
An Internet Protocol (IP) address is a numerical label like a phone number or street address assigned to a device to identify the host connected to a computer network and allows it to send and receive data over that network. IP addresses are expressed as a set of four numbers called octets each separated by a delimiter (period). This expression is called dotted-decimal notation and is found in use with the IPv4 address structure. Each number in an IP address can span from 0-255 and can be converted down to binary. IPv4 addresses are 32-bit (4 bytes) in length and can fall under one of the five following classes;
Private IP Class Ranges:
Class A: 10.0.0.0 - 10.255.255.255
Class B: 172.16.0.0 - 172.31.255.255
Class C: 192.186.0.0 - 192.168.255.255
Class D (Multicast): 224.0.0.0 - 239.255.255.255
Class E (Experimental): 240.0.0.0 - 254.255.255.254
Subnet Masks:
Class A: 255.0.0.0
Class B: 255.255.0.0
Class C: 255.255.255.0
Attributes: (an address can also be public or private and static or dynamic).
Public - assigned to devices that are accessible from the internet.
Private - assigned to devices on a private network that are not directly accessible from the internet.
Static - a manually set address remains the same over time.
Dynamic - an automatically set address can change over time.
Loopback Addresses:
A loopback address is also known as localhost or 127.0.0.1. This is an internal Class A set of addresses that directs network traffic back to the same device. It is used for testing network software and hardware on the local machine and ensuring that the TCP/IP stack is functioning properly. The range for this set of address ranges from 127.0.0.0 - 127.255.255.255 with a subnet mask of 255.0.0.0. However, 127.255.255.255 is the broadcast address for 127.0.0.0/8.