Application layer protocols
1. Telnet
Telnet is an application protocol. It offers a bidirectional, interactive text-focused conversation
capability. Telnet employs a terminal connection for text-based communication. Telnet can be used to
configure certain networking hardware components. In an 8-bit byte-oriented data connection at TCP,
data is interspersed in-band with Telnet control information. Telnet is a form of client-server protocol
that is used to launch the command line on distant computers.
2. FTP
File Transfer Protocol is what it's called. For the purpose of transferring a file from one place to another,
or from one host to another host, it is an application layer protocol. TCP/IP offers a common technique
for doing so. It may appear extremely simple to convert files from one system to another, but there are
several issues that must be resolved beforehand. The TCP services are used. There must be two TCP
connections. There are two connections: a control connection and a data connection. It uses well-known
port 21 for control connections and well-known port 20 for data connections.
3TFTP
Trivial File Transfer Protocol (TFTP), also known as an application layer protocol, is used to transfer files
from a server to a client. The UDP protocol is used by the trivial file transfer protocol to transfer files
from the server to the client. User Datagram Protocol is used here. It is typically used to transfer files
between computers that are only connected to a local intranet. The main advantage of trivial file
transfer protocol is that it consumes little memory. If computers don't have hard drives, this application
layer protocol might be used to transmit boot files. The port for communication can be specified when
Trivial File Transfer Protocol is set up, but it typically uses protocol 69.
4SMTP
SMTP is short for The emails are transferred using a straightforward mail transfer protocol. It outlines
the requirements for sending back and forth between instructions and answers. It is used twice: once
between the two mail servers and once between the sender and the sender's mail server. Simple mail
transfer protocol employs commands and answers to transport messages between message transfer
agents client and message transfer agents server. Message Transfer Agents, or MTAs, handle the actual
mail transfer. To send mail from one system to another, the system needs both client and server
message transfer agents.
5 SNMP
Simple Network Management Protocol, or SNMP, is a tool for gathering and organizing data from
controlled devices on IP networks. Additionally, it alters the data to alter how the devices behave. The
major purposes of SNMP are network management and monitoring. It comprises of a collection of
protocols for the application layer, a database schema, and a number of data items for network
management.
6 DNS
DNS stands for Domain Name System is a decentralized naming system for the computers and other devices on the
internet to translate the domain name of the devices connected on the internet or any other private network to the
numerical IP addresses and vice versa. Advantage of DNS is that the user does not need to remember the IP address
of the domain. DNS support TCP protocol and UDP protocol. DNS server works on the port 53.Domains are
categorized into three parts generic domains, country domains, and inverse domains, where generic domains define
registered hosts according to their generic behavior, country domains use two characters country abbreviation,
inverse domain maps address to map.
7. DHCP
DHCP stands for Dynamic Host Configuration Protocol. It is a network management protocol present in the
application layer. With its help, an Internet Protocol IP address can be assigned to any device or node on a network
dynamically so that they can communicate using this IP. The main goal of DHCP protocol is to assign unique IP
addresses to the hosts. Apart from Unique IP address, it also provides other network address such as subnet mask,
Router address, vendor class identifier, and DNS address. A DHCP server has a pool of addresses for a device to get
a valid network connection..
