Common Applications
The network is not very useful without applications. Applications are software programs that communicate over the network or processes that give access to the network. There are two types of applications: network applications and application layer services.
Network Applications
Network applications communicate over the network. Some end-user applications apply application layer protocols and can communicate directly with the lower layers of the protocol stack. For example, Email clients are network applications.
Application Layer Services
Network print spooling and file transfer over the network are requisite application layer services for using network resources. These services are the software programs that interface with the network and organize the data for transfer. Several types of data, e.g., text, graphics, audio, and video, are wanted different network services to ensure the data is ready for processing.
Each application or network service uses protocols describing the data standards and formats. There is no way to format data without standard network protocols. Before understanding the role of network services, understanding protocols is very important. In the Windows operating system, we can view the current application, services, and running process, as shown in the above figure. The following are the standard protocols used in networking:-
DNS
DNS was created to convert a numeric address into a simple, recognizable name. DNS stands for Domain Name System (Service or Server).
Telnet
Telnet is a service that allows network administrators to log in to a host remotely and control it just like they are working locally.
Email Server
SMTP, POP3, or IMAP send email messages from clients to servers over the Internet.
DHCP Server
DHCP is the service that automatically assigns the IP address, subnet mask, default gateway, and other information to clients.
Web Server
Web servers transfer information and data between web clients and web servers. The majority of websites are accessed through HTTP (Hypertext Transfer Protocol)
FTP Server
The FTP service allows the download and upload of files between a client and a server.
Voice and Video Applications
Streaming media is very important for businesses to communicate with customers and business partners. The network administrators must care about the equipment configuration and installation and ensure it meets the requirements of real-time applications. The administrator also determines whether the present switches and cabling can support the traffic that will be added shortly.
VoIP
VOIP stands for Voice Over Internet Protocol. In standard terms, VOIP is a call service over the Internet.
VOIP requires a quality Internet connection to get phone service through an Internet connection instead of the local phone company. We can also use VoIP with traditional phone service because VOIP service providers typically offer lower call rates than traditional phone services.
We can also use a traditional phone set with an ATA (analogue telephone adapter), which converts the analogue signal into digital IP packets and vice versa. The administrator can attach the device between a traditional analogue phone and the Ethernet switch. VoIP is much less expensive than an integrated IP telephony solution, but the quality does not meet the same standards.
IP Telephony
In IP telephony, the ATA adapter is no longer required because the IP phone itself performs the voice-to-IP conversion. IP phones also use a separate server for call control and signaling.
Real-time Applications
A real-time application is a software program that works within a time frame the user senses as current. This software uses the Real-Time Transport Protocol (RTP) and Real-Time Transport Control Protocol (RTCP).
The QoS mechanism controls the latency of less than a defined value, usually measured in seconds. For example, video conferencing applications, online gaming, and video chatting are Real-time applications.