Key Concepts · solulu

What happens when you enter google.com in the web browser?

A sequence of steps occurs to fetch and render the content.

Check the browser cache first if the content is fresh and present in the cache display the same.
If not, the browser checks if the IP of the URL is present in the cache (browser and OS) if not then requests the OS to do a DNS lookup using UDP to get the corresponding IP address of the URL from the DNS server to establish a new TCP connection.
A new TCP connection is set between the browser and the server using three-way handshaking.
An HTTP request is sent to the server using the TCP connection.
The web servers running on the Servers handle the incoming HTTP request and send the HTTP response.
The browser processes the HTTP response sent by the server and may close the TCP connection or reuse the same for future requests.
If the response data is cacheable then browsers cache the same.
Browser decodes the response and renders the content.

Hub vs Switch

Networking devices used to connect nodes.

Hub: Hub is a networking device which is used to transmit the signal to each port (except one port) to respond from which the signal was received. Hub is operated on a Physical layer. In this packet filtering is not available. It is of two types: Active Hub, Passive Hub.
Switch: Switch is a network device which is used to enable the connection establishment and connection termination on the basis of need. Switch is operated on the Data link layer. In this packet filtering is available. It is a type of full duplex transmission mode and it is also called an efficient bridge.

Subnet

A subnet is a network inside a network achieved by the process called subnetting which helps divide a network into subnets. It is used for getting a higher routing efficiency and enhances the security of the network. It reduces the time to extract the host address from the routing table.

Network Reliability

The reliability of a network can be measured by several factors.

Downtime: The downtime is defined as the required time to recover.
Failure Frequency: It is the frequency when it fails to work the way it is intended.
Catastrophe: It indicates that the network has been attacked by some unexpected event such as fire, earthquake.

Effective Network Criteria

There are mainly two criteria which make a network effective and efficient.

Performance : performance can be measured in many ways like transmit time and response time.
Reliability: reliability is measured by frequency of failure.
Robustness: robustness specifies the quality or condition of being strong and in good condition.
Security: It specifies how to protect data from unauthorized access and viruses.

Node and Link

A network is a connection setup of two or more computers directly connected by some physical mediums like optical fiber or coaxial cable. This physical medium of connection is known as a link, and the computers that it is connected to are known as nodes.

Gateway and Router

A node that is connected to two or more networks is commonly known as a gateway. It is also known as a router. It is used to forward messages from one network to another. Both the gateway and router regulate the traffic in the network. Differences between gateway and router: A router sends the data between two similar networks while gateway sends the data between two dissimilar networks.

NIC (Network Interface Card)

NIC stands for Network Interface Card. It is a peripheral card attached to the PC to connect to a network. Every NIC has its own MAC address that identifies the PC on the network. It provides a wireless connection to a local area network. NICs were mainly used in desktop computers.

POP3 (Post Office Protocol version 3)

POP is responsible for accessing the mail service on a client machine. POP3 works on two models such as Delete mode and Keep mode.

Private vs Public IP

IP addresses are categorized based on their accessibility.

Private IP Address - There are three ranges of IP addresses that have been reserved for IP addresses. They are not valid for use on the internet. If you want to access the internet on these private IPs, you must use a proxy server or NAT server.
Public IP Address - A public IP address is an address taken by the Internet Service Provider which facilitates communication on the internet.

RAID

RAID (Redundant Array of Inexpensive/Independent Disks): It is a method to provide Fault Tolerance by using multiple Hard Disc Drives.

Netstat

Netstat : It is a command line utility program. It gives useful information about the current TCP/IP setting of a connection.

Ping

The “ping” is a utility program that allows you to check the connectivity between the network devices. You can ping devices using its IP address or name.

Peer-to-Peer (P2P)

The processes on each machine that communicate at a given layer are called peer-peer processes. (P2P).

Casting Types

Methods of sending messages across a network.

Unicasting: If the message is sent to a single node from the source then it is known as unicasting. This is commonly used in networks to establish a new connection.
Anycasting: If the message is sent to any of the nodes from the source then it is known as anycasting. It is mainly used to get the content from any of the servers in the Content Delivery System.
Multicasting: If the message is sent to a subset of nodes from the source then it is known as multicasting. Used to send the same data to multiple receivers.
Broadcasting: If the message is sent to all the nodes in a network from a source then it is known as broadcasting. DHCP and ARP in the local network use broadcasting.