Please enable JavaScript.

Coggle requires JavaScript to display documents.

REDES - Coggle Diagram

- - - - The upper three layers of the OSI model (application, presentation, and session) define functions of the single TCP/IP application layer.
        
        Some of the most widely known application layer protocols include Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Trivial File Transfer Protocol (TFTP), Internet Message Access Protocol (IMAP), and Domain Name System (DNS) protocol.
- - - - The session layer handles the exchange of information to initiate dialogs, keep them active, and to restart sessions that are disrupted or idle for a long period of time
  - - - Encrypting data for transmission and decrypting data upon receipt
- - - - DHCP
  - - - POP
        
        IMAP
  - - - TFTP
  - - - This is referred to as dynamic addressing. The alternative to dynamic addressing is static addressing.
        
        When using static addressing, the network administrator manually enters IP address information on hosts.
        
        The DHCP server chooses an address from a configured range of addresses called a pool and assigns (leases) it to the host.
        
        New users may arrive and need connections; others may have new computers that must be connected.
        
        The DHCP server in most medium-to-large networks is usually a local, dedicated PC-based server.
        
        With home networks, the DHCP server is usually located on the local router that connects the home network to the ISP.
        
        DHCP is used for general purpose hosts, such as end user devices.
        
        Rather than use static addressing for each connection, it is more efficient to have IPv4 addresses assigned automatically using DHCP.
        
        One important difference is that DHCPv6 does not provide a default gateway address.
        
        Users can freely move from location to location and easily re-establish network connections through DHCP.
        
        Static addressing is used for network devices, such as gateways, switches, servers, and printers.
- - - - n addition to the actual data transfer, this exchange may also require user authentication and the identification of a data file to be transferred.
  - - - The email client on a home computer issues a request to the ISP’s email server for any unread mail.
- - - - In a P2P network, two or more computers are connected via a network and can share resources (such as printers and files) without having a dedicated server.
        
        Every connected end device (known as a peer) can function as both a server and a client.
        
        The roles of client and server are set on a per request basis.
- - - - Some P2P applications use a hybrid system where resource sharing is decentralized, but the indexes that point to resource locations are stored in a centralized directory.
        
        In a hybrid system, each peer accesses an index server to get the location of a resource stored on another peer.
- - - - eDonkey
      - G2
      - BitTorrent
      - Bitcoin
  - - - This file also contains information about tracker computers that keep track of which users have what files. Clients ask for pieces from multiple users at the same time, known as a swarm.
- - - - Using HTTP requirements, the browser sends a GET request to the server and asks for the index.html file.
        
        he server, as shown in Figure 3, sends the HTML code for this web page to the browser. Finally, as shown in Figure 4, the browser deciphers the HTML code and formats the page for the browser window.
- - - - HTTPS uses the same client request-server response process as HTTP, but the data stream is encrypted with Secure Socket Layer (SSL) before being transported across the network.
- - - - Email clients communicate with mail servers to send and receive email.
      - An email client does not communicate directly with another email client when sending email.
        
        Email supports three separate protocols for operation: Simple Mail Transfer Protocol (SMTP), Post Office Protocol (POP), and IMAP.
        
        The application layer process that sends mail uses SMTP.
        
        A client retrieves email, however, using one of the two application layer protocols: POP or IMAP.
- - - - After the connection is made, the client attempts to send the email to the server across the connection.
    - - The destination email server may not be online or may be busy when email messages are sent.
        
        Therefore, SMTP spools messages to be sent at a later time. Periodically, the server checks the queue for messages and attempts to send them again
- - - - When the connection is established, the POP server sends a greeting.
        
        The client and POP server then exchange commands and responses until the connection is closed or aborted.
        
        With POP, email messages are downloaded to the client and removed from the server, so there is no centralized location where email messages are kept.
        
        Because POP does not store messages, it is undesirable for a small business that needs a centralized backup solution
- - - - The original messages are kept on the server until manually deleted. Users view copies of the messages in their email client software.
      - Users can create a file hierarchy on the server to organize and store mail.
        
        That file structure is duplicated on the email client as well. When a user decides to delete a message, the server synchronizes that action and deletes the message from the server.
- - - - 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
      - If it is unable to resolve the name using its stored records, it contacts other servers to resolve the name.
        
        After a match is found and returned to the original requesting server, the server temporarily stores the numbered address in the event that the same name is requested again.
        
        The DNS Client service on Windows PCs also stores previously resolved names in memory.
- - - - DNS is scalable because hostname resolution is spread across multiple servers.
        
        .com - a business or industry
        
        .org - a non-profit organization
        
        .au - Australia
        
        .co - Colombia
    - - When a DNS server receives a request for a name translation that is not within its DNS zone, the DNS server forwards the request to another DNS server within the proper zone for translation.
- - - - when the nslookup command is issued, the default DNS server configured for your host is displayed.
    - - The nslookup utility has many options available for extensive testing and verification of the DNS process.
    - - This utility can also be used to troubleshoot name resolution issues and to verify the current status of the name servers.