3.2 Understand Transport layer protocols (3.3.3 Explain common…
3.2 Understand Transport layer protocols
3.3.3 Explain common Applications layer protocols
SMTP, POP and IMAP
The header must have a properly formatted recipient email address and a sender address.
Users use email clients to retrieve messages stored on the server.
SMTP message formats require a message header and body.
Messages are downloaded from the server to the client.
POP allows for email messages to be downloaded to the client’s device (computer or phone) and removed from the server.
A downloaded message resides on the device that triggered the download.
MAP is another protocol used to retrieve email messages.
Allows for messages to be displayed to the user rather than downloaded.
When a user decides to delete a message, the server synchronizes that action and deletes the message from the server.
DNS (Domain Name Service )
Computers still need the actual numeric address before they can communicate.
The DNS protocol allows for the dynamic translation of a domain name into the associated IP address.
IP addresses are not easy to memorize.
DHCP e. FTP (Dynamic Host Configuration Protocol) (File Transfer Protocol )
IP information include host and gateway addresses, mask, and DNS server.
Computers need network IP information to communicate over a network.
DHCP-distributed addresses are leased for a set period of time.
FTP was developed to allow the transfer of files over the network.
An FTP client is an application that runs on a client computer used to push and pull data from an FTP server.
FTP requires two connections between the client and the server: one connection for commands and replies and another connection for the actual file transfer.
The client can download (pull) data from the server or upload (push) data to the server.