Module 16 Netacad

Domain Name System (DNS)

Resolves internet names to IP addresses

Secure Shell (SSH)

Used to provide remote access to servers and networking devices

Simple Mail Transfer Protocol (SMTP)

Sends email messages and attachments from clients to servers and from servers to other email servers

Dynamic Host Configuration Protocol (DHCP)

Used to automatically configure devices with IP addressing and other necessary information to enable them to communicate over the internet

Hypertext Transfer Protocol (HTTP)

Used by web browsers to request web pages and web servers to transfers the files that make up web pages of the World Wide Web

nslookup Command

this command is used to find the IP address of a domain name (e.g., www.cisco.com). It queries DNS servers and is helpful for troubleshooting DNS issues. It works in both Windows and Linux.

HTTP & HTML

this protocol is used to request web pages from servers (via port 80). The server sends the page back, which is coded in this to tell the browser how to display it, including text, images, and layout. it is the standard language for structuring web pages.

HTTPS Protocol

this is the secure version of HTTP, using encryption to protect data. It runs on port 443 and starts with "https://" in the browser. It keeps information safe during transmission, unlike regular HTTP, which is not secure.

File Transfer Protocol (FTP)

this protocol is used to transfer files between computers over a network. It uses two ports: TCP port 21 for control messages (connection setup) and TCP port 20 for transferring data. it allows users to upload, download, and manage files remotely, and is supported by most operating systems and web browsers.

Telnet

a protocol that allows remote access to a server through a text-based interface, acting like a "virtual terminal" over the network. It connects to the server using TCP port 23 and enables users to run commands on the server as if they were physically connected. However, however it is not secure, so SSH is often used instead for secure remote access.

SMTP (Simple Mail Transfer Protocol)

this protocol is used to send emails from an email client to the local server and between servers when the message needs to be forwarded. It operates on port 25 and helps deliver emails to the correct destination, whether local or on another server.

POP3 (Post Office Protocol)

this protocol is used by email clients to download messages from the server. Once the messages are downloaded, they are typically removed from the server. it operates on port 110 and is ideal for users who want to store emails locally on their device and don't need to access them from multiple locations.

IMAP4 (Internet Message Access Protocol)

this protocol allows email clients to access and manage messages stored on the server. Unlike POP3, this keeps emails on the server (unless deleted by the user), making it ideal for accessing emails from multiple devices. it operates on port 143.

Text Messaging (Instant Messaging)

this enables real-time communication between users over the internet. Both clients can send and receive messages simultaneously, and many platforms also support file sharing, video, and audio. Popular apps include WhatsApp, Microsoft Teams, and Facebook Messenger.

VoIP (Voice over IP)

this enables making telephone calls over the internet by converting analog voice signals into digital data, which is sent through IP packets. Users typically call others by selecting their username, and calls to regular phones require a gateway to connect to the PSTN.