What is the OSI seven-tier model? What functions are they responsible for?

  1. The application layer

Provides data transfer services between applications. Common protocols include Http, DNS, and SMTP

  1. The presentation layer

Responsible for data compression, encryption, and data representation, which eliminates the need for applications to care about the internal format of data in different hosts.

  1. The session layer

Responsible for creating and managing sessions

  1. The transport layer

Provides data transmission services between different processes. Common protocols include TCP and UDP

  1. The network layer

Provides data transmission services between different hosts and provides routing and data packet storage and forwarding functions

  1. Data link layer

Provides data transfer services between hosts on the same link

  1. The physical layer

Bitstreams can be transmitted over different media regardless of differences in underlying transmission media