Appendix
B.1 Terms
SCALANCE W1750D UI
554
Configuration Manual, 02/2018, C79000-G8976-C451-02
Term
Definition
DNS Server
A Domain Name System (DNS) server functions as a phonebook for the Internet and Internet users. It
converts human readable computer hostnames into IP addresses and vice-versa.
A DNS server stores several records for a domain name such as an address 'A' record, name server
(NS), and mail exchanger (MX) records. The Address 'A' record is the most important record that is
stored in a DNS server, because it provides the required IP address for a network peripheral or ele-
ment.
DST
Daylight saving time (DST), also known as summer time, is the practice of advancing clocks, so that
evenings have more daylight and mornings have less. Typically clocks are adjusted forward one hour
near the start of spring and are adjusted backward in autumn.
EAP
Extensible authentication protocol (EAP) refers to the authentication protocol in wireless networks that
expands on methods used by the point-to-point protocol (PPP), a protocol often used when connecting
a computer to the Internet. EAP can support multiple authentication mechanisms, such as token cards,
smart cards, certificates, one-time passwords, and public key encryption authentication.
fixed wireless
Wireless devices or systems in fixed locations such as homes and offices. Fixed wireless devices usu-
ally derive their electrical power from the utility mains, unlike mobile wireless or portable wireless which
tend to be battery-powered. Although mobile and portable systems can be used in fixed locations,
efficiency and bandwidth are compromised compared with fixed systems.
frequency alloca-
tion
Use of radio frequency spectrum regulated by governments.
frequency spect-
rum
Part of the electromagnetic spectrum.
hotspot
A WLAN node that provides Internet connection and virtual private network (VPN) access from a given
location. A business traveler, for example, with a laptop equipped for Wi-Fi can look up a local hot spot,
contact it, and get connected through its network to reach the Internet and their own company remotely
with a secure connection. Increasingly, public places, such as airports, hotels, and coffee shops are
providing free wireless access for customers.
IEEE 802.11
standards
The IEEE 802.11 is a set of standards that are categorized based on the radio wave frequency and the
data transfer rate.
POE
Power over Ethernet (PoE) is a method of delivering power on the same physical Ethernet wire used
for data communication. Power for devices is provided in one of the following two ways:
•
Endspan— The switch that an AP is connected for power supply.
•
Midspan— A device can sit between the switch and APs
The choice of endspan or midspan depends on the capabilities of the switch to which the AP is con-
nected. Typically if a switch is in place and does not support PoE, midspan power injectors are used.
PPPoE
Point-to-Point Protocol over Ethernet (PPPoE) is a method of connecting to the Internet typically used
with DSL services where the client connects to the DSL modem.
QoS
Quality of Service (QoS) refers to the capability of a network to provide better service to a specific net-
work traffic over various technologies.
RF
Radio Frequency (RF) refers to the portion of electromagnetic spectrum in which electromagnetic
waves are generated by feeding alternating current to an antenna.
TACACS
Family of protocols that handle remote authentication and related services for network access control
through a centralized server.
Derived from TACACS but an entirely new and separate protocol to handle AAA services.
uses TCP and is not compatible with TACACS. Because it encrypts password, username, authoriza-
tion, and accounting, it is less vulnerable than RADIUS.