Telnet, FTP – e-mail – DNS

TELNET

Telnet (Telecommunication Network) is a protocol used for remotely accessing and managing devices over a network, typically the internet. It allows a user to establish a text-based connection to a remote server or device and interact with it as if they were directly connected to the device's console 

Telnet operates on the Application Layer of the OSI model and uses a client-server architecture. 

The client application (telnet client) initiates a connection to the remote server (telnet server) using the Telnet protocol. Once the connection is established, the user can send text commands to the server and receive text-based responses. 

Telnet sessions are typically used for tasks such as remote administration, configuration, and troubleshooting of devices such as routers, switches, servers, and other network equipment. 

Advantages of Telnet

It provides remote access to one's computer system.

Telnet allows the user to have more access with less problems in data transmission.

telnet saves a lot of time.

The oldest system can be connected to a newer system with different operating systems with telnet.

• As it is somewhat complex, it becomes difficult for beginners to understand.

• Some capabilities are disabled because of not proper interlinking of the remote and local devices.

• Data is sent here in plain text form, that's why it is not so secure.

• File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. 

• FTP is built upon a client–server model architecture using separate control and data connections between the client and the server.

The main purpose of FTP is to facilitate the uploading and downloading of files between computers. It's often used for tasks such as

• Uploading website files to a web server.

• Downloading software updates from a remote server.

• Sharing files between users on a network.

• Backing up files to a remote server.

Speed- One of the biggest benefits of FTP is speed. The FTP is one of the fastest way to transfer files from one computer to another.

Efficient: It is more efficient as we do not need to complete all the operations to get the whole file.

Security-To access the FTP server, we need to login with username and password. So we can say that FTP is more secure.

Back & forward movement- FTP allows us to transfer the files back and forth. Suppose you are a manager of the company, you send some information to all the employees, and all of them send information back on the same server.

• File size limit is the drawback of FTP only 2GB size files can be transferred.

• Multiple receivers are not supported by the FTP.

• FTP does not encrypt the data this is one of the biggest drawbacks of FTP.

• FTP is unsecured, we use login IDs and passwords making it secure but they can be attacked by hackers.

A way of sending electronic messages or data from one computer to another.

A worldwide e-mail network allows people to exchange e-mail messages very quickly 

Email, short for “electronic mail,” is a method of exchanging digital messages over the Internet. 

It allows people to send and receive messages and files to and from each other using electronic devices such as computers, smartphones, and tablets. 

Email has become one of the most common and widely used forms of communication both in personal and professional contexts.

DNS stands for Domain Name System, and it is a fundamental technology used on the Internet to translate human-readable domain names into IP addresses. 

Computers and servers communicate with one another using IP addresses, which are numerical identifiers for devices on a network. 

However, remembering and typing the IP addresses for every website you want to visit would be impractical for humans.

DNS acts as a distributed directory system that allows users to access websites and other online resources using easily memorable domain names (like www.example.com) rather than numerical IP addresses. 

Here is how it works:

1.User Input- When you enter a domain name (eg, www.example.com) into your web browser, your device needs to know the IP address associated with that domain to establish a connection.

2.DNS Query- Your device sends a DNS query to a DNS resolver (typically provided by your Internet Service Provider or a third-party service), asking for the IP address of the domain.

3.DNS Resolving Process – The DNS resolver doesn't have the IP address cached in most cases, so it begins a process to find the IP. It first checks its cache to see if it has recently resolved this domain. If not, it proceeds to find out that information.

4.Authoritative DNS Server- The authoritative DNS server for the domain holds the information about the domain's IP address (and potentially other records like mail server settings). It answers to the resolver's query with the required IP address.

5.Response to User – The resolver receives the IP address from the authoritative server and caches it for future use. It then sends back the IP address to your device.

6.Establishing Connection – With the IP address in hand, your device can now establish a connection with the web server hosting the website you want to visit

7.Recursive Query- If the resolver does not have the answer, it sends a series of queries to different DNS servers. It begins by asking the root DNS servers for information about the top-level domain (TLD), then proceeds to the authoritative DNS servers responsible for the TLD. These authoritative servers direct the resolver to the DNS servers responsible for a specific domain (e.g., example.com).