Who invented the Internet Protocol?

Vinton Cert
In a research paper published in 1974, Vinton Cerf and Robert Kahn proposed a protocol they called "TCP". Cerf and Kahn didn't realize it at the time, but the protocol they invented would later become IP, the official network-layer protocol of the Internet.







Robert Kahn
In May, 1974, the Institute of Electrical and Electronic Engineers (IEEE) published a paper titled "A Protocol for Packet Network Interconnection." The paper's authors -- Vinton Cerf and Robert Kahn -- described a protocol called "TCP" that incorporated both connection-oriented and datagram services.
.It soon became apparent to the two men that this design should be subdivided into two separate protocols. Session management was not easy to do in an application-independent way. In practice, an application could sometimes run more efficiently or be implemented more easily when it managed network connections itself. "TCP" became Internet Protocol (IP) that supported datagrams and Transmission Control Protocol (TCP/IP) that added connection semantics as a layer on top of IP.

Workgroup and Domain in Windows

Workgroup and Domain in Windows

Workgroup
A collection of computers that share resources, advised not more than 10 PCs.
Each computer has its own database located locally, maintains its own accounts, administration and security policies and shares resources with all other computers. In essence, all computers are of equal status.

Within a company, different departments may be workgroups and each may have a unique name to identify the workgroup.


Domain
A domain is a logical collection of computers that share resources. Somehow you need a SERVER that is responsible for managing security and other user-related information for the domain. This server allows login validation, by which a user logs into the domain and not into a single computer.

TCP/IP, Subnet Mask and Default Gateway

TCP/IP, Subnet Mask and Default Gateway

What is TCP/IP for?
Computers have a common "language" that they use to talk to each other on the Net, which is called Transmission Control Protocol/Internet Protocol(TCP/IP). its ability to connect together different sizes networks and different type of networking operating system.

When you are connected directly to the Internet, your computer accesses a copy of the TCP/IP language, as does every other connected computer regardless of their particular operating system. When your computer utilizes this language it can communicate with other computers.

TCP/IP
In OSI Model, TCP at Transport Layer manages the assembling of a message or file into smaller "packets" that are transmitted over the Internet and received by a TCP layer on the receiving computer that reassembles the packets into the original message.

The Internet Protocol (IP) handles the address of each packet so that it gets to the right destination.

Three important components to a TCP/IP address: IP address, subnet mask, and default gateway.

IP Address
Ip Address looks like: 172.16.52.63

There are classes for IP address; Class A, B, C, D, E.
Class A, B, C allocated by the InterNIC (http://www.internic.net/(http://www.internic.net)), the organization that administers the Internet. each of which can be divided into smaller subnetworks by system administrators.

How to identify the class of an IP address?
• Class A networks use a default subnet mask of 255.0.0.0 and have 0-127 as their first octet. The address 10.52.36.11 is a class A address. Its first octet is 10, which is between 1 and 126.

• Class B networks use a default subnet mask of 255.255.0.0 and have 128-191 as their first octet. The address 172.16.52.63 is a class B address. Its first octet is 172, which is between 128 and 191, inclusive.

• Class C networks use a default subnet mask of 255.255.255.0 and have 192-223 as their first octet. The address 192.168.123.132 is a class C address. Its first octet is 192, which is between 192 and 223.

• Class D & E for future use.

Subnet Mask
A subnet mask is used to divide an IP address into two parts.
One part identifies the host (computer), the other part identifies the network to which it belongs.

For example:
A subnet Mask: 255.255.0.0

The numbers that make up the subnet mask indicate which portion of the IP address is the network number and which portion is the computer number. The four numbers of the subnet mask correspond directly to the four numbers in the IP address.

if you had a computer with an IP address of 147.100.100.25 and a subnet mask of 255.255.0.0, the first two numbers in the subnet mask (both are 255) indicate that the first two numbers of the IP address are the network number. The second two numbers (both are 0) indicate that the second two numbers of the IP address are the computer number. Therefore, in the IP address 147.100.100.25, the 147.100 portion denotes which network the computer is located on, and the 100.25 portion represents a particular computer on that network.

Default Gateway
For computers on your network to talk to computers on another network, you need a default gateway. The default gateway is a computer to which other local computers send data that is destined for a non-local computer.

When computers attempt to communicate with other computers that are not local to the IP address range they belong to (the subnet they belong to), the local computers must send their data to the default gateway to be forwarded.

For Example:
Suppose you have a network with a node called Host 100 and a node called Host 200. Note that Host 100 is located on Network 1 and Host 200 is located on Network 2. Assume that Host 100 addresses and sends a packet to Host 200. After Host 100 checks its local routing tables and is unable to resolve the “path” to Host 200, it forwards the packet to the default gateway.

Windows Internet Name Service (WINS)

Windows Internet Name Service (WINS)

For clients who use the latest technology of Windows system, their PCs communicate with other Host on an Internet Protocol (IP) by using Domain Name System (DNS). However, clients that use older versions of Windows, such as Windows 95, 98, ME, NT 4.0, use network basic I/O system (NetBIOS) names for network communication.

So, in order for these PCs communicate properly nowadays, all these NetBIOS need to resolve into IP address. The Hosts(Servers) must have WINS installed to resolve NetBIOS to IP address for PCs which are still running the old version of Windows system and Unix boxes running Samba.

WINS features
WINS Server:
A computer that processes name registration requests from WINS clients, registers the client's name and IP addresses, and responds to NetBIOS name queries that clients submit. The WINS server then returns the IP address of a queried name, if the name is listed in the server database.

WINS database:
the WINS database stores and replicate the NetBIOS name to IP address mappings for a network.

WINS Client:
Computers that are directly pointing to a WINS server to register their NetBIOS name and to communicate with other computers registered with same WINS server on that network.

WINS proxy agents:
A computer that monitors broadcast for name query and give responds for all those names which are not located on the local subnet. WINS server communicates with the proxy for resolving names and then it caches the names for a particular time period.


How does WINS works?
As soon as a WINS client obtains the IP configuration from the DHCP server (or on bootup if the WINS server’s IP address was statically assigned), the WINS client issues a NameRegistrationRequest message to the WINS server. Unlike standard NetBIOS behavior, this message isn’t a broadcast. It is a message sent only to the primary WINS server and includes the client’s computer name and IP address.

The WINS server checks to see whether the computer name is listed in its database. If it isn’t listed, the WINS server assumes that it’s unique on the network and responds with a positive WINS name registration response.

The registration response includes a period called the time-to-live (TTL) during which the registration is valid. If the name isn’t unique, a negative response is sent to the client, and the WINS server sends a challenge to the name’s current owner. Typically, the computer that currently owns the name acknowledges that it is alive on the network and the negative response message informs the new computer that there is a conflict.