If we are within the network and want to establish connections with other computers, we need to know its IP 192.168.l.2 address. IP address of each computer must know another. Because otherwise it would be impossible to distinguish with which computer you want to communicate. One computer may have more IP addresses. If it has more network adapters.

The abbreviation IP 192.168.l.2 stands for Internet Protocol

The IP address is of the form xxx.xxx.xxx.xxx, where xxx is a number in the range of 0 to 255 – or one byte, since we have 4 bytes, thus the address is 32 bits (one byte = 8 bits -> 4×8 = 32 ), it is the standard IPv4, IPv6 is another standard in which the address is 128 bits.

IPv4 address might look like this: 192.168.l.2 – for the sake of clarity, however, each IP address can (and does not) have been assigned. Domain name (hostname). For example, if you want to get to the site of Bill Gates and not to a memorable mix of hard numbers, but you just need to browse to the www.bill.gates.microsoft.com. You can see what is ping. One IP address can be assigned multiple domain names – the principle of virtual servers on a single machine – for example, you have a web hosting company XY and she has one server, which hosts more domains for more customers. Also one machine can have multiple IP addresses – for example, for load balancing if they are overloaded mail or web server.

IP addresses can not just arbitrarily invented. Allocates the international authority responsible for managing IP addresses. The currently used 32 bit IPv4. Because it allows addressing only four billion computers (theoretically 4,294,967,296 IP addresses), a new version IPv6. IPv6 has 128 bits and will for its implementation should be about – 2005 – 2015.

Separation of IPv4 addresses:

An IP address 192.168.l.2 consists of two parts net – ID (network address) and host – ID (computer address). Depending on how large the individual networks (how they are) distinguishes three main classes of IP addresses – A, B and C.

class A
IP address class A in the Czech Republic, nobody has. They have it especially multinational companies, government organizations, etc. USA. Allows addressing of only 126 networks, but each of them may be up to 16 million computers. Value range of IP addresses: to 127,255,255,255.

class B
Class B allows addressing already 16,000 networks and 65,000 hosts on each network. The first two byte address is the network address and the other two computers. In the Czech Republic it has a significant organization. The range of values in the class B is: to 191,255,255,255.

class C
Class C IP address can address up to 2 million networks. Each network can be 254 computers. Class C IP address is the most widely used in the Czech Republic. The first three bytes are the network address and a byte address of the computer. The range is: up 223255255255
Special IP addresses

Some IP addresses 192.168.l.2 are reserved for special purposes:

Range from to is included in Class D. This class is used for multicasting. That means for broadcasting the video or audio.

Range from to 247 255 255 255 belongs to the class E. These values are reserved for future use and for experimental purposes. and are intended for testing purposes. They called the loopback address.
These addresses used by network software. If you send data to this address will be broadcast via any of the computer’s network adapters to the network. Only we find out whether it is functional software, regardless of whether it works when network hardware.

Network addresses, ie. The address whose host part of all zeros. These addresses are used by the IP protocol for proper routing of packets between networks.

Broadcast address, 192.168.l.2 is open to all guests in the network. They are used for mass sending of packets.

192.168.l.2 addresses (ie. Localhost, the most commonly used address are reserved for so-called. Loopback, logical loop lets you send packets to itself.

Intranet, if the network is isolated, without an Internet connection, you can use any IP address. When you connect the internal network to the Internet, it could happen that will existivat same two IP addresses. This fact prevents proxy gateways. Proxy Gateway can be used for any service TCP / IP.

Proxy is actually a computer that is connected in any way to the Internet. Must have a real IP address to see “out” and the “outside” was visible.
When you write some web addresses to computers on the internal network, the browser sends the query to the proxy gateway. She asks her name on the Internet and then passes the request back to the computer. And on nearby computers set addresses reserved for internal networks. IP reserved for internal network:

Class A: to 10,255,255,255
Class B: to
Class C: to 192,168,255.0

Separation of IPv6 addresses:

The IPv6 address has a length of 128 bits, which means that the number of possible addresses 2128 ≈ 3 x 1038th This is astronomically large number; an idea: in theory it is a 6 x 1023 IP addresses per 1 sqm land surface. Even if we include that in IPv6 is needed large part of the book addresses and the address space can not be fully utilized, there is enough addresses to each device connected to the Internet with their own unique address.

IPv6 address is written as eight groups of four hexadecimal digits, for example: 2001: 0718: 1c01: 0016: 0214: 22ff: fec9: 0ca5

Leading zeros in each group can be skipped. Thus, the above address can be written as: 2001: 718: 1c01: 16: 214: 22ff: fec9: CA5

If the address contains several consecutive zeros, you can instead write only “::”. This acronym may be only one address. Often used for prefixes for addresses ending with zeros or for special addresses, such as loopback (loop) whose shape :: 1 is more than 0000: 0000: 0000: 0000: 0000: 0000: 0000: 0001.

IPv6 address architecture defines RFC 4291. In introduces three types of addresses:

Individual (unicast) identifying single network interface.
Group (multicast) identify a group of network interfaces, to whose members the data should be delivered. Group addressed datagram is delivered to all members of the group.

Selective (192.168.l.2) also referred to a group of network interfaces, data will not only deliver its closest member.



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