Basic definitions of the Web. About IP Addresses
For Internet technologies, there are basic concepts, without knowledge of which the understanding of the principles and methods of its functioning will be quite superficial. Those who want to understand in detail and deeply on the basis of what the World Wide Web functions on should understand the terminology and know the basic definitions of the Network regarding its operation.
Each PC connected to the Network has its own unique personal address, by which all devices identify each other. There should not be two addresses with the same value on the Internet. The format for writing the address is reduced to a single standard defined by the IP protocol. Recording is done on a 32-bit system. Each of the four groups is determined by decimal numbers in the range 0 – 255. If you look at this entry from the point of view of the binary code, we will see the sequences 0 and 1. Thus, the IP address is represented by a record through the point of four groups of digits, for example, 126.96.36.199 . Today, there are more than four billion original and completely unique records of each of the existing IP addresses.
IP is assigned not only to a separate PC or laptop, but also to any devices connected to the Internet, for example, routers. For all devices included in the Internet, one common name is accepted as a host or otherwise a host. Interestingly, in some cases, several IP addresses can be assigned to the same physical device. This happens when several different network adapters are installed on the same device. In this case, each of them receives its own unique address. Devices with several adapters are called a router if they are used to connect different local networks.
In order to quickly determine the data transfer route between local networks, in each router it is necessary to store information about the addresses of the devices that go to each of these networks. Given their number, not a single router can physically provide storage of such a huge number of values in memory. To indicate the location of the device, the address is divided into two separate parts: the first shows the local network number, the second shows the address of a specific device in it. This can be compared with the entry in the address of the location of a person on the street and the specification of the place by the number of the house.
All devices connected in a network with one number are grouped into logical networks, between which communication is provided by the routers responsible for transmitting information. This process is defined by the term routing. In order to ensure the security of information transfer and targeted communication between logical networks (address translation, information filtering, and so on), other devices with a special purpose are used, they are combined according to the general term gateway.
Subnets. Subnet masks
Individualization of addresses for a standalone network greatly simplifies, but does not completely solve routing problems. This is especially true of large-sized local networks, which caused them to be divided into subnets when each has its own address. In other words, a subnet is a part of the same network that is independently functioning separately from others and is assigned its own identifier number. In the IP address, when specifying the address value of the subnet, space is allocated in the host address values. At the same time, they are determined by the subnet mask. The mask parameters are written in the same form as the IP address: in the form of four groups of numbers, where the dot is used as a separator. To determine the values of the groups, it is customary to understand that all the bits in the octet recorded in the value 1 correspond to the host identifier parameter. A value of 0 indicates the identifier of a particular node. The netmask can only be considered in conjunction with the address of the immediate node.
In the process of viewing the IP address of the mask by the IP protocol, the address of a specific network, a specific subnet, and a specific host are individualized.
Static and dynamic IP addresses
The basic rule for each IP address is its uniqueness. It is set in two ways. The first one is the manually set IP addresses for each computer, which are assigned to it by the network administrator when configuring the TCP / IP protocol. Such an address fixed to the device is called static. It is considered an advantage to have a static or permanent IP value, as this makes it possible to personalize your device and can be used to use additional security features when working on the World Wide Web. For example, this is true if you are the administrator of a group of sites on a remote server. So you get the opportunity to set a restriction on entry, allowing it only to your device and only from a specific specifically resolved IP address.
If your device is not assigned a static IP address, it can be assigned automatically by DHCP.