CCNA Ch 15 Application Layer
DNS, Some of these record types are as follows:
A - An end device IPv4 address NS - An authoritative name server AAAA - An end device IPv6 address (pronounced quad-A) MX - A mail exchange record
Session Layer
As the name implies, functions at the session layer create and maintain dialogs between source and destination applications.
Host config
BOOTP - Bootstrap Protocol DHCP - Dynamic Host Configuration Protocol
Common P2P Applications
BitTorrent Direct Connect eDonkey Freenet
Name system
DNS - TCP UDP 53
File Transfer
FTP - File Transfer Protocol TFTP - Trivial File Transfer Protocol
Presentation Layer
Formatting, or presenting, data at the source device into a compatible format for receipt by the destination device. Compressing data in a way that can be decompressed by the destination device. Encrypting data for transmission and decrypting data upon receipt.
Web
HTTP - Hypertext Transfer Protocol HTTPS - HTTP Secure
Application layer protocols
Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Trivial File Transfer Protocol (TFTP), Internet Message Access Protocol (IMAP), and Domain Name System (DNS) protocol.
Client-Server Model
In the client/server model, the device requesting the information is called a client and the device responding to the request is called a server. The client is a hardware/software combination that people use to directly access the resources that are stored on the server.
Peer-to-Peer Networks
In the peer-to-peer (P2P) networking model, the data is accessed from a peer device without the use of a dedicated server.
presentation layer formats data for the application layer, and it sets standards for file formats. Some well-known standards for video include
Matroska Video (MKV), Motion Picture Experts Group (MPG), and QuickTime Video (MOV) Some well-known graphic image formats are Graphics Interchange Format (GIF), Joint Photographic Experts Group (JPG), and Portable Network Graphics (PNG) format.
TCP/IP Application Layer Protocols
Name system Host config Email File Transfer Web
Gnutella
Peer-to-peer applications based on *THIS* protocol, people can make files on their hard disks available to others for downloading.
SMTP - Simple Mail Transfer Protocol POP3 - Post Office Protocol IMAP - Internet Message Access Protocol
Here are three functions of SMB messages:
Start, authenticate, and terminate sessions. Control file and printer access. Allow an application to send or receive messages to or from another device.
DNS Hierarchy
The DNS protocol uses a hierarchical system to create a database to provide name resolution, as shown in the figure. DNS uses domain names to form the hierarchy.
Server Message Block
The Server Message Block (SMB) is a client/server file sharing protocol that describes the structure of shared network resources, such as directories, files, printers, and serial ports.
BitTorrent
file-sharing software that allows users to create "swarms" of data as they simultaneously download and upload "bits" of a given piece of content
