15. In the seven-layer OSI model of computer networking, the network
layer is layer 3. The network layer is responsible for packet forwarding
including routing through intermediate routers.
The network layer is the third level (Layer 3) of the Open Systems
Interconnection Model (OSI Model) and the layer that provides data routing
paths for network communication. ... Logical connection setup, data
forwarding, routing and delivery error reporting are the network layer's
primary responsibilities
The role of the Network Layer is to enable any two open systems
anywhere to exchange data with one another, irrespective of the types
of network the two systems are attached to and of the means of
interconnecting those two networks.
Located at Layer 3 of the Open Systems Interconnection (OSI)
communications model, the primary function of the network layer is to move
data into and through other networks.
The main functions of network layer is to provide end-to-end addressing,
routing and to provide a connectionless datagram delivery of
packets.
14. Private and Public IP Address
A public IP address identifies you to the wider internet so that all the
information you're searching for can find you. A private IP address is used
within a private network to connect securely to other devices within that
same network. Each device within the same network has a unique private
IP address.
Private (internal) addresses are not routed on the Internet and no traffic
can be sent to them from the Internet, they only supposed to work within
the local network. Private addresses include IP addresses from the
following subnets: Range from 10.0. 0.0 to 10.255.
A public IP address is an IP address that can be accessed directly over
the internet and is assigned to your network router by your internet
service provider (ISP). Your personal device also has a private IP that
remains hidden when you connect to the internet through your router's
public IP.
for example, google.com
13. IP fragmentation is an Internet Protocol process that breaks packets
into smaller pieces, so that the resulting pieces can pass through a link with
a smaller maximum transmission unit than the original packet size. The
fragments are reassembled by the receiving host.
Fragmentation is necessary for data transmission, as every network has
a unique limit for the size of datagrams that it can process. This limit is
known as the maximum transmission unit (MTU).
Fragmentation most generally means the process of fragmenting—
breaking into pieces or being divided into parts. It can also refer to the
state or result of being broken up or having been divided.
Examples: Hydra, Spirogyra, etc.
12. What is meant by parity check?
a method for detecting errors in data communications or within a
computer system by counting the number of ones or zeros per byte or per
word, including a special check bit (parity bit ), to see if the value is even or
odd.
What is the purpose of using parity check bit?
A parity bit is a check bit, which is added to a block of data for error
detection purposes. It is used to validate the integrity of the data. The
value of the parity bit is assigned either 0 or 1 that makes the number of 1s
in the message block either even or odd depending upon the type of parity.
There are two kinds of parity bits: In even parity, the number of bits with
a value of one are counted. ... In odd parity, if the number of bits with a
value of one is an even number, the parity bit value is set to one to make
the total number of ones in the set (including the parity bit) an odd number.
11. Framing is a point-to-point connection between two computers or
devices consists of a wire in which data is transmitted as a stream of
bits. ... Framing is a function of the data link layer. It provides a way for a
sender to transmit a set of bits that are meaningful to the receiver.
Frames can be of fixed or variable size. In fixed-size framing, there is no
need for defining the boundaries of the frames; the size itself can be used
as a delimiter. An example of this type of framing is the ATM wide-area
network, which uses frames of fixed size called cells.
In variable - length framing, the size of each frame to be transmitted
may be different. So, a pattern of bits is used as a delimiter to mark the
end of one frame and the beginning of the next frame
Types of Framing
Framing can be of two types, fixed sized framing and variable sized framing.
Fixed-sized Framing
Here the size of the frame is fixed and so the frame length acts as delimiter
of the frame. Consequently, it does not require additional boundary bits to
identify the start and end of the frame.
Example − ATM cells.
Variable – Sized Framing
Here, the size of each frame to be transmitted may be different. So additional
mechanisms are kept to mark the end of one frame and the beginning of the
next frame.
It is used in local area networks.
10. What do u mean by socket?
Definition: A socket is one endpoint of a two-way communication link
between two programs running on the network. A socket is bound to a
port number so that the TCP layer can identify the application that data is
destined to be sent to. An endpoint is a combination of an IP address and a
port number.
Example. An Internet Protocol (IP) addressable client and server, for
example, might engage in an e-mail transfer using SMTP (Simple Mail
Transfer Protocol), which is well-known port 25.
Top 10 Types of Sockets
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Stream Sockets. These sockets are used on the delivery side of the
network environment. ...
Datagram Sockets. The implementation doesn't give any guaranteed
delivery as they work connectionless. ...
Raw Sockets. ...
Packet Sequenced Sockets. ...
Hex Sockets. ...
Socket Bit. ...
Impact Sockets. ...
Spark Plug Sockets.
There are four common socket sizes: 1/4 inch (0.6 centimeters), 3/8 inch
(0.9 centimeters), 1/2 inch (1.3 centimeters) and 3/4 inch (1.9
centimeters).
9. The Address Resolution Protocol is a communication protocol used for
discovering the link layer address, such as a MAC address, associated with
a given internet layer address, typically an IPv4 address. This mapping is a
critical function in the Internet protocol suite.
Address Resolution Protocol (ARP) is used to dynamically map layer-3
network addresses to data-link addresses.
The address resolution protocol (arp) is therefore used to translate between
the two types of address.
There are four types of ARP.
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Proxy ARP.
Reverse ARP (RARP)
Gratuitous ARP.
Inverse ARP.
8. The mechanism for exchange of information between different computer
networks and network segments is called switching in Networking.
Switching may be applied in various formats and can function in diverse ways
within a greater network infrastructure.
There are three types of message switching techniques used:
1. Circuit Switching In-Circuit Switching, a dedicated channel is
established for a single connection where the sender and receiver
can communicate during the communication session.
2. Message Switching There is no dedicated path established between
the sender and receiver in message switching, as in circuit switching.
3. Packet Switching In packet switching, when we send a message,
then the whole message is divided into smaller pieces called packets.
These pieces or packets travel across the network and take the
shortest path as possible.
7. The two are essentially the same, in that both of them refer to the same
“hypertext transfer protocol” that enables requested web data to be
presented on your screen. But, HTTPS is still slightly different, more
advanced, and much more secure. Simply put, HTTPS protocol is an
extension of HTTP.
HTTPS is HTTP with encryption. The only difference between the two
protocols is that HTTPS uses TLS (SSL) to encrypt normal HTTP
requests and responses. As a result, HTTPS is far more secure than
HTTP. A website that uses HTTP has http:// in its URL, while a website that
uses HTTPS has https://.
HTTP is unsecured while HTTPS is secured. HTTP sends data over port
80 while HTTPS uses port 443. HTTP operates at application layer, while
HTTPS operates at transport layer. ... No encryption in HTTP, with HTTPS
the data is encrypted before sending.
6. Network address translation is a method of mapping an IP address
space into another by modifying network address information in the IP
header of packets while they are in transit across a traffic routing device.
A. Network Address Translation (NAT) is designed for IP address
conservation
For example a computer on an internal address of 192.168. 1.10 wanted to
communicate with a web server somewhere on the internet, NAT would
translate the address 192.168. 1.10 to the company's public address, lets
call this 1.1.
Where is NAT used?
The main use of NAT is to limit the number of public IP addresses an
organization or company must use, for both economy and security
purposes.
The most popular type of NAT configuration, Overloading is a form of
dynamic NAT that maps multiple unregistered IP addresses to a single
registered IP address (many-to-one) by using different ports. It's also
known as Port Address Translation (PAT).
5. Internet Control Message Protocol
The Internet Control Message Protocol (ICMP) is a protocol that devices
within a network use to communicate problems with data transmission.
A good example is the “ping” utility which uses an ICMP request and
ICMP reply message. When a certain host of port is unreachable, ICMP
might send an error message to the source.
The Internet Control Message Protocol (ICMP) is a network layer protocol
used by network devices to diagnose network communication issues. ICMP
is mainly used to determine whether or not data is reaching its intended
destination in a timely manner. Commonly, the ICMP protocol is used on
network devices, such as routers. ICMP is crucial for error reporting and
testing, but it can also be used in distributed denial-of-service (DDoS)
attacks.
4.
A port is a virtual point where network connections start and end.
Ports are software-based and managed by a computer's operating
system. Each port is associated with a specific process or service.
A Computer Port is an interface or a point of connection between the
computer and its peripheral devices.
Ports are standardized across all network-connected devices, with
each port assigned a number. Most ports are reserved for
certain protocols — for example, all Hypertext Transfer Protocol
(HTTP) messages go to port 80
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PS/2
Serial Port
o DB-25
o DE-9 or RS-232 or COM Port
Parallel Port or Centronics 36 Pin Port
Audio Ports
o Surround Sound Connectors or 3.5 mm TRS Connector.
3. A virtual circuit (VC) is a means of transporting data over a packetswitched network in such a way that it appears as though there is a
dedicated physical link between the source and destination end systems
of this data. The term virtual circuit is synonymous with virtual
connection.
Virtual circuit switching is a packet switching methodology whereby a
path is established between the source and the final destination through
which all the packets will be routed during a call. This path is called
a virtual circuit because to the user, the connection appears to be a
dedicated physical circuit.
Public networks offer two types of virtual circuit--permanent and
switched.
An example of a circuit-switched network is an analog telephone
network.
2. A datagram is a basic transfer unit associated with a packetswitched network. Datagrams are typically structured in header and
payload sections. Datagrams provide a connectionless communication
service across a packet-switched network. Datagram:
This term is basically synonymous with “packet” and is also used to
refer to network layer technologies. It is also often used to refer to a
message that is sent at a higher level of the OSI Reference Model (more
often than “packet” is).
A datagram is primarily used for wireless communication and is selfcontained with source and destination addresses written in the header. It
is similar to a packet, which is a small piece of data transmitted through
a connectionless protocol.
Datagram packet-switching is a packet switching technology by which
each packet, now called a datagram, is treated as a separate entity.
Structure
Each datagram has two components, a header and a data payload. The
header contains all the information sufficient for routing from the originating
equipment to the destination without relying on prior exchanges between
the equipment and the network. Headers may include source and
destination addresses as well as a type field. The payload is the data to be
transported. This process of nesting data payloads in a tagged header is
called encapsulation.
1. Packet forwarding is the basic method for sharing information across
systems on a network. Packets are transferred between a source interface
and a destination interface, usually on two different systems. When you
issue a command or send a message to a nonlocal interface, your system
forwards those packets onto the local network. The interface with the
destination IP address that is specified in the packet headers then retrieves
the packets from the local network. If the destination address is not on the
local network, the packets are then forwarded to the next adjacent network,
or hop. By default, packet forwarding is automatically configured when you
install Oracle Solaris.
Routing is the process by which systems decide where to send a packet.
Routing protocols on a system “discover” the other systems on the local
network. When the source system and the destination system are on the
same local network, the path that packets travel between them is called
a direct route. If a packet must travel at least one hop beyond its source
system, the path between the source system and destination system is
called an indirect route. The routing protocols learn the path to a
destination interface and retain data about known routes in the
system's routing table.
End