CCNA Cisco Certified Network Associate Study Guide - FTP Server

TCP/IP and the DoD Model 105
has been sent to a destination, the message is spooled to a device—usually a
disk. The server software at the destination posts a vigil, regularly checking
this queue for messages. When it detects them, it proceeds to deliver them to
their destination. SMTP is used to send mail; POP3 is used to receive mail.
Line Printer Daemon (LPD)
The Line Printer Daemon (LPD) protocol is designed for printer sharing. The
LPD, along with the LPR (Line Printer) program, allows print jobs to be
spooled and sent to the network’s printers using TCP/IP.
X Window
Designed for client-server operations, X Window defines a protocol for the
writing of graphical user interface–based client/server applications. The idea
is to allow a program, called a client, to run on one computer and have it display
a program called a window server on another computer.
Simple Network Management Protocol (SNMP)
Simple Network Management Protocol (SNMP) collects and manipulates
this valuable network information. It gathers data by polling the devices on
the network from a management station at fixed or random intervals, requiring
them to disclose certain information. When all is well, SNMP receives
something called a baseline—a report delimiting the operational traits of a
healthy network. This protocol can also stand as a watchdog over the network,
quickly notifying managers of any sudden turn of events. These network
watchdogs are called agents, and when aberrations occur, agents send
an alert called a trap to the management station.
Domain Name Service (DNS)
Domain Name Service (DNS) resolves host names, specifically Internet
names, like www.routersim.com. You don’t have to use DNS; you can just
type in the IP address of any device you want to communicate with. An IP
address identifies hosts on a network and the Internet as well. However,
DNS was designed to make our lives easier. Also, what would happen if you
wanted to move your Web page to a different service provider? The IP
address would change and no one would know what the new one was. DNS
allows you to use a domain name to specify an IP address. You can change
the IP address as often as you want and no one will know the difference.