Fundamentals of network administration. What is IP-address

More and more users on the InternetThey try to find out what an IP address is, in order to take advantage of the acquired knowledge for their specific purposes. Someone was banned on their favorite site by IP, someone wants to surf the net anonymously or set up an internal Intranet. For such tasks, you need to understand the principle of the functioning of network devices using the TCP | IP protocol.

Indeed, network interaction occursin most cases it is by this protocol, and each computer is determined by a unique numeric address that identifies the network participant. To understand what an IP address is, let's find out the meaning of this term. We will also consider the range of IP-addresses (given the concept) and search the site in the browser for its domain name.

What is the numerical address of the computer

This is a unique identifier separating the host fromwhich to the computer receives any data (over the network) or from which certain data is sent from the computer to the network. This designation is applicable not only to computers, but also to any other devices that support communication via the TCP | IP driver.

The web resource can also reveal its geographical location up to a specific region.

What is the IP address in the visual representation. Internal IP

Here is an example of an internal numeric address inlocal area network (LAN): 198.169.1.1. In this case, the first 3 decimal digits denote a TCP / IP network (a number of interconnected computers on the internal subnet). The last number "personalizes" a unique host in this subset.

Unlike the global identifiers (WAN)internal addresses can not function in the Internet space and characterize only a local subnet. Internet access in this case is carried out through a router or a proxy server.

In other words, the host address is like 198.169.1.1 or 10.12.2.254 is an internal one. There is a certain range of IP addresses (subnets) that will never be part of the Internet zone. The converse is also true: no computer on the global subnet can be defined by an identifier of type 192.169.1.X, where X is the IP address of the individual device.

How the browser "looks" for a website by typing in the address bar of the name

Let's figure out what an IP address is from the browser's point of view and why its presence is necessary to identify the resource.

So, when in Internet Explorer or another browser the user enters the site address, the following process occurs.

The IP corresponding to the symbolicname of the resource (dns-resolution). In this case, the browser first accesses a special file with a list of mappings. If the desired mapping is not present in the list, the software calls for "help" to the DNS service specified in the operating system settings.

This service independently finds the necessary address-identifier, and transfers the received result to the browser.

Now the browser "knows" what the IP-address of the final resource is and where the user's request should be sent. As a result, the user sees before himself the web page he wanted to receive.

How the IP address is issued

In a local network consisting of a set ofcomputers and intermediate devices, assigning each individual ID manually is too troublesome and irrational. For this process, there is a dedicated host on which the dynamic delivery service is configured from the range of IP addresses - DHCP.

This service is usually configured in such a way,that when a single host is accessed, a specific IP is output from a certain range of local addresses. Also, the network mask parameters and, possibly, the network router address are transmitted to the host, without which an output to an adjacent or global subnet is impossible. The other hosts must have a DHCP client installed.