Network Questions

1)What is LAN?

LAN is a computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a wide-area network (WAN). Most LANs connect workstations and personal computers. Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it also is able to access data and devices anywhere on the LAN. This means that many users can share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions.

2) Explain the 7 Layers of OSI.

Layer 1: Physical layer

It represents all the electrical and physical specifications for devices. 

Layer 2: Data link layer

It provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical layer.

Layer 3: Network layer

The Network layer provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks.

Layer 4: Transport layer

It provides transparent transfer of data between end users.

Layer 5: Session layer

It controls the sessions between computers. It connects, manages and terminates the connections between the local and remote application.

Layer 6: Presentation layer

It transforms data to provide a standard interface for the Application layer.

Layer 7: Application layer

It provides a means for the user to access information on the network through an application. 

3) Explain IP, TCP and UDP.

TCP – Transmission control Protocol is used to establish communication between nodes or networks and exchange data packets. It guarantees delivery of data packets in the order they were sent. Hence it is most commonly used in all applications that require guaranteed delivery of data. It can handle both timeouts (if packets were delayed) and retransmission (if packets were lost). The stream of data is transmitted in segments. The segment header is 32 bit. it is a connectionless communication protocol at the third level (network) of the OSI model.

IP – Internet protocol is used for transmission of data over the internet. IP uses IP addresses to identity each machine uniquely. Message is sent using small packets. The packet contains both the sender and receivers address. IP does not guarantee the delivery in the same order as sent. This is because the packets are sent via different routes. It is a connectionless communication protocol at the third level (network) of the OSI model.

UDP – User Data Protocol is a communication protocol. It is normally used as an alternative for TCP/IP. However there are a number of differences between them. UDP does not divide data into packets. Also, UDP does not send data packets in sequence. Hence, the application program must ensure the sequencing. UDP uses port numbers to distinguish user requests. It also has a checksum capability to verify the data. 

4) What is a MAC address? 

A Media Access Control address is a unique identifier that is assigned to the network adapters or NICs by the manufacturers for the purpose of identification and used in the Media Access Control protocol sub layer. It is a 12 digit hexadecimal number. A MAC address usually encodes the registered identification of the manufacturer, if the address is assigned by the manufacturer. It some times also called as Ethernet Hardware Address / physical address/ adapter address

5 )Explain the functionality of PING.

Ping Is particularly used to check if the system is in network or not. It also gives packet lost information. In windows ping command is written as ping ip_address. The output returns the data packets information. The number of packets sent, received and lost is returned by PING.