Without applications, the network is not too useful. The applications are software programs that used to communicate over the network or process that giving access to the network. The application has two types, network application and application layer services.
The network applications are used to communicate over the network. Some end-user applications apply application layer protocols and are able to communicate straight with the lower layers of the protocol stack. Email clients are the example of this type of application.
Application Layer Services
Network print spooling and file transfer over the network is required application layer services to use 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 required different network services to make sure that the data is perfectly ready for processing.
Each application or network service uses protocols, which describe the standards and formats to be used for data. There is no way to format data without common network protocols. Before understanding the role of network services, the understanding of 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. Following are the common protocols uses in networking:-
DNS was created to change the numeric address into a simple, recognizable name. The DNS is short for Domain Name System (or Service or Server).
Telnet is a service that allows network administrators to log in to a host remotely and control the host just like they are working locally.
SMTP, POP3, or IMAP are used to send email messages from clients to servers over the Internet.
DHCP is the service that assigns the IP address, subnet mask, default gateway, and other information to clients automatically.
Web server is used to transfer information and data between web clients and web servers
the majority of websites are accessed using HTTP (Hypertext Transfer Protocol)
The FTP service allows download and uploads files between a client and server
Voice and Video Applications
Streaming media is too much important for businesses to communicate with customers as well as their business partners. The network administrators must care that the equipment is properly configured, installed and it’s meet the requirements of real-time applications. The administrator must determine whether the present switches and cabling can support the traffic that will be added in near future.
VOIP stands for Voice Over Internet Protocol. In common terms, VOIP is call service over the Internet.
VOIP is required quality Internet connection for getting a phone service through Internet connection instead of the local phone company. VoIP can also be used with traditional phone service because VOIP service providers typically give low call rates than traditional phone services.
We can use a traditional phone set using ATA (analog telephone adopter). The ATA adopter converts the analog signal into digital IP packets and vice versa. The device is attached between a traditional analog phone and the Ethernet switch. VoIP is too much less expensive than an integrated IP telephony solution, but the quality does not meet the same standards
In IP telephony the ATA adopter is no more required because the IP phone itself performs the voice-to-IP conversion. The IP phones use a separate server for call control and signaling.
A real-time application is a software program that works within a time frame that the user senses as current. This kind of software uses Real-Time Transport Protocol (RTP) and Real-Time Transport Control Protocol (RTCP). The QoS mechanism controls the latency of less than a defined value, which usually measured in seconds. Video conferencing application, online gaming video chatting are the examples of Real-time applications