The transport layer uses the ​ (a)   to establish an ​ (b)   with the recipient computer. It ​ (c)   into packets and ​ (d)   them sequentially. Adds the ​ (e)   to be used based on the HTTP protocol.

The ​ (a)   layer uses the ​ (b)   to address packets with the source and ​ (c)   IP addresses. A router forwards each packet to an endpoint called a ​ (d)   defined by the combination of IP address and ​ (e)   .

When receiving data at the destination:

The Link Layer removes the ​ (a)   from each packet and passes it to the Network Layer. The Network Layer removes the ​ (b)   from each packet and passes it to the ​ (c)   Layer. The Transport Layer removes the ​ (d)   from each packet, reassembles the packets in the correct order and passes them to the Application Layer. The ​ ​ (e)   Layer presents the data for the user in a browser.

A ​ (a)   uniquely identifies a ​ (b)   device with a Network Interface Card (NIC). This may be the ​ (c)   computer, or a ​ (d)   in transit. Packets move up and down the lower layers of the stack as they hop across routers, changing their source and ​ (e)   MAC addresses as they go

File Transfer Protocol is an ​ (a)   level protocol used to ​ (b)   across a network. FTP uses the ​ (c)   model with separate data and control ​ (d)   operating on ports 20 and 21. Usernames and passwords are frequently used to protect access to files and to identify users. Access can also be provided ​ (e)   where any user can access the FTP site.

SSH can be used to create a (a)   through a network.

​ (a)   Used to send emails and forward them between mail servers to their destination. ​ (b)   Downloads email stored on a ​ (c)   to a local client (removed after download). ​ (d)   Manages emails on a server so ​ (e)   clients can access the same email account in synchronicity.