User`s manual

Glossary
Connection : A link between machines, applications, processes, etc. that can be logical, physical, or both.
DNS, Domain Name Service : A service that converts symbolic node names to IP addresses.
Ethernet : A local-area network (LAN) architecture that uses a bus or star topology and supports data transfer
rates of 10 Mbps. Ethernet is one of the most widely implemented LAN standards. A newer version of
Ethernet, called 100Base-T (or Fast Ethernet), supports data transfer rates of 100 Mbps. And the newest
version, Gigabit Ethernet supports data rates of 1 gigabit (1,000 megabits) per second.
External interface : The DFL-500 interface that is connected to the Internet.
FTP, File transfer Protocol : An application and TCP/IP protocol used to upload or download files.
Gateway : A combination of hardware and software that links two different types of networks. Gateways
between TCP/IP networks, for example, can link different subnetworks.
HTTP, Hyper Text Transfer Protocol : The protocol used by the World Wide Web. HTTP defines how
messages are formatted and transmitted, and what actions Web servers and browsers should take in
response to various commands.
HTTPS : The SSL protocol for transmitting private documents over the Internet using a Web browser.
Internal interface : The DFL-500 interface that is connected to your internal (private) network.
Internet : A collection of networks connected together that span the entire globe using the NFSNET as their
backbone. As a generic term, it refers to any collection of interdependent networks.
ICMP, Internet Control Message Protocol : Part of the Internet Protocol (IP) that allows for the generation of
error messages, test packets, and information message relating to IP. This is the protocol used by the ping
function when sending ICMP Echo Requests to a network host.
IKE, Internet Key Exchange : A method of automatically exchanging keys between two secure servers.
IMAP, Internet Message Access Protocol : An Internet email protocol that allows access to your email from
any IMAP compatible browser. With IMAP, your mail resides on the server.
IP, Internet Protocol : The component of TCP/IP that handles routing.
IP Address : An identifier for a computer or device on a TCP/IP network. The format of an IP address is a 32-
bit numeric address written as four numbers separated by periods. Each number can be zero to 255.
L2TP, Layer Two (2) Tunneling Protocol : An extension to the PPP protocol that enables ISPs to operate
Virtual Private Networks (VPNs). L2TP merges PPTP from Microsoft and L2F from Cisco Systems. To create
a L2TP VPN your ISP's routers must support L2TP.
IPSec, Internet Protocol Security : A set of protocols that support secure exchange of packets at the IP
layer. IPSec is most often used to support VPNs.
LAN, Local Area Network : A computer network that spans a relatively small area. Most LANs connect
workstations and personal computers. Each computer in a LAN is able to access data and devices anywhere
on the LAN. This means that many users can share data and resources such as printers.
MAC address : Media Access Control address, a hardware address that uniquely identifies each node of a
network.
Modem : A device that converts digital signals into analog signals and back again for transmission over
telephone lines.
MTU , Maximum Transmission Unit : The largest physical packet size, measured in bytes, that a network
can transmit. Any packets larger than the MTU are divided into smaller packets before being sent. Ideally, you
want the MTU your network produces to be the same as the smallest MTU of all the networks between your
machine and a message's final destination. If your messages are larger than one of the intervening MTUs,
they get broken up (fragmented), which slows down transmission speeds.
Netmask : Also called subnet mask. A set of rules for omitting parts of a complete IP address to reach a
target destination without using a broadcast message. It can indicate a subnetwork portion of a larger network
in TCP/IP. Sometimes referred to as an Address Mask.
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