A) Wireless
Ethernet (233 – 266)
a. Wireless LAN (Wireless Ethernet) – a local
area network that is not based primarily on physical wiring but uses wireless
transmission between workstations
i. Components
of a wireless LAN
1. User device
must have a NIC that can receive and transmit wirelessly
2. Wired local
area network
3. Access point – the interface device
between the wireless user device and the wired local area network
ii. Configurations
of a wireless LAN
1. Single-cell
wireless LAN – at the center of the cell is the access point which is connected
to the wired LAN. All user devices communicate with this one access point and
compete for the same set of frequencies. This standard is called Basic Service Set (BSS)
2. Multiple
cells are supports by multiple access points, as in a cellular telephone
network. Users communicate with the nearest access point and may move from one
cell to another
3. Peer-to-Peer
(Ad hoc layout) – no access point at the center of a cell, each user device
communicates directly with the other user device
b. Wireless
LAN Standards
i. IEEE 802 suite of protocols was
created to support the many different types of wireless local area networks in
existence
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IEEE 802.11b
|
11 Mbps using 2.4 GHz
|
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IEEE 802.11g
|
54 Mbps using 2.4 GHz
|
|
IEEE 802.11a
|
54 Mbps using 5GHz
|
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IEEE 802.11ac
|
Uses 5GHz
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ii. Multiple input multiple output (MIMO) –
technique in which both the mobile device and the access point have multiple,
smart antennae that help to reduce signal interference and reflections
iii. Wired equivalent privacy (WEP) – security
protocol for wireless LAN, not powerful enough to stop wiretapping and key was
too small and not changeable
iv. Wi-Fi Protected Access (WPA)
1. Temporary Key Integrity Program (TKIP) – uses
128.bit key on each packet and it changes with each packet transmitted, making
it nearly impossible for an unauthorized user with a wireless device to connect
to a WPA-protected signal
v. Wi-Fi Protected Access II (WPA2) – uses CCMP
(counter mode with cipher block chaining message authentication code protocol)
instead of TKIP
c. Wireless
CSMA/CA
i. Carrier sense multiple access with collision
avoidance (CSMA/CA) – if a user device wishes to transmit and the
medium is idle, the device is not allowed to transmit immediately. Instead, the
device is made to wait for a small period of time called the initerframe space (IFS). If the medium
is still idle after this interframe space, the device is then allowed to
transmit
B) Network
Operating Systems
a. Operating System – program
initially loaded into computer memory when the computer is turned on; it
manages all the other programs (Applications) and resources (such as disk
drives, memory, and peripheral devices) in a computer
i. Even after
an application starts and is being executed, the application makes use of the
operating system by making service requests through a defined application programming interface (API)
ii. Multitasking operating system – multiple
programs can be running at the same time. In this case, the operating system
schedules each task and allocates a small amount of time for the execution of
that task
iii. Network operating system (NOS) – large,
complex program that can manage the common resources on most local area
networks, in addition to performing the standard operating system services
mentioned previously
C) Network
operating systems past and present
a. Novell
NetWare
i. NetWare Directory Services (NDS) – an
intelligent system that authenticates users and includes a distributed database
of information about every application, user, server, and resource on a network
ii. Redirection – when print requests are
automatically forwarded to another printer on the network
iii. Bindery – structure (similar to a
database) that contains the usernames and passwords of network users and group
of users authorized to log in to that server; it consists of three linked,
nonidentical files that are encrypted for security reasons
iv. Organizational unit (OU) – an object
that is further composed of additional objects (examples of which include
servers, printers, users, or groups of users)
v. Leaf objects – not composed of any
objects and are usually entities such as the users, peripherals, servers,
printers, queues, and other network resources
b. Microsoft
Windows NT and Windows Server
i. Windows NT
Version 4
1. Domain – container object that contained
users, servers, printers, and other network resources
a. Not hierarchical
ii. Windows
Server 2000
1. Active directory – stores information
about all the objects and resources in a network and makes this information
available to users, network administrators, and application programs
iii. Windows
Server 2003
1. Updates to
the Active directory, including a new management tool that unifies all the
tasks related to group policy
2. Capability to
interconnect (cluster) up to eight Windows 2003 servers for better user and
application support
3. New and
improved file and printer support services, including increased reliability,
wider range of supported printers, and remote document sharing
4. Support for
internet protocol version 6 (IPv6)
5. Better security
features for files, networks, servers, the operating system, and web-based
transactions
iv. Windows
Server 2008 and 2012
c. UNIX –
popular operating system that can be found on single-user workstations as well
as on mainframe computers and servers. Most often found with a text-based
interface
d. Linux – based
on UNIX concept and is a complete rewrite of the UNIX kernel and borrows
additional functions from the well-established Free Software Foundation’s GNU
toolset and from the even larger free software community
e. Mac OS X
Server – capable of supporting both Macintosh and Windows workgroups, and is based
on software created by the open-source community
D) Servers
a. Server – the computer that stores
software resources such as the network operating system, computer application,
programs, databases, and performs one or more network-type services for
attached clients
b. Redundant Array of Independent Disks (RAID) – collection
of techniques for interfacing multiple hard disk drives to a computer
i. RAID-0 – data is broken into pieces, and
each piece is stored on different disk drives, known as stripping
ii. RAID-1 – data stored on at least 2 disk drives, in duplicate, disk mirroring
iii. RAID-3 – data is redundantly stored
across multiple hard drives (stripping) and error-checking information
concerning the stored data is kept on a separate disk. This error-checking is
used to detect errors and possibly reconstruct the data should some of it
become corrupted
iv. RAID-5 – data is broken into pieces
(stripes) and stored across three or more disks. Parity information
(error-checking code) is stored along with the stripped data, not on a separate
disk
c. Server virtualization – making one
computer (or server) act as if it were multiple computers (or servers)
d. Server appliance – single unit
or box that supports many networking functions such as internet sharing,
intranet Web serving, firewall security, FTP services, file and print serving,
e-mail service, and virtual private network configurations
e. Server blade – server that has no
cabinet or box but resides on a single printed circuit card
f. Peer-to-peer network – allows communications
between workstations, as if the workstations were all equal
E) Network
support software
a. Utilities – software programs that
operate in the background and support one or more functions to keep the network
running at optimal performance
i. Antivirus software – designed
to detect and remove viruses that have infected the computer’s memory, disks,
or operating system
ii. Spam – unsolicited commercial bulk
e-mail
1. Anti-spam
software – used to block this unwanted e-mail
iii. Spyware – software that a user unknowingly
downloads from the internet, and when this software is executed on the user’s
machine, it begins spying on the user
1. Anti-spyware software – can located
and clean the spyware programs found in a computer’s memory and hard disk drive
iv. Backup software – allows network
administrators to back up data files currently stored on a server’s hard disk
drive
v. Crash protection software – performs
crash stalling or to try to keep the operating system running long enough to
perform a graceful exit
vi. Network-monitoring software –
incorporates a fairly large number of network support tools
1. Sniffers – can “listen” to traffic on a
network and determine if invalid messages are being transmitted, report network
programs such as malfunctioning NICs, and detect traffic congestion problems
vii. Remote access software – allows a
user to access all of the possible functions of a personal computer workstation
from a mobile or remote location
viii. Security assessment software – designed to
scan an IP address or a range of IP addresses for any type of security weakness
1. May include
ports that are open, improperly designed shares and trusts, suspicious
processes running in the background, and known vulnerabilities in the operating
system that have not yet been corrected
ix. Uninstall software – works with
the user to locate and remove applications that are no longer desired
b. Internet software – toolset to
support internet-related services
i. Web server software –
application or set of programs that store web pages and allows browsers from
anywhere in the world to access those web pages
F) Software Licensing Agreements – legal contract
that describes a number of conditions that must be upheld for proper use of the
software package
a. Single-user-single-station license – software package
may be installed on a single machine and then only a single user at one time
may use that machine
b. Single-user-multiple-station license – designed
for the user who might have a desktop machine at work and a laptop machine for
remote sites, or another desktop machine at home
c. Interactive user license –
operating system user license, and controlled number of concurrent user’s
license all refer to essentially the same situation. When a software package is
installed on a multiuser system, it is possible for multiple users to execute
multiple copies of a single program
d. Server license – rarely a
software counter controlling the current number of users
e. Site license – allows a software package
to be installed on any and all workstations and servers at a given site
f. Corporate license – allows a
software package to be installed anywhere within a corporation, even if
installation involved multiple sites
g. General Public License (GPL) –
associated with software that is free to share and change
G) Lan support
devices
a. Uninterrupted Power Supply (UPS) – a
battery backup device that can maintain power to one or more pieces of
equipment for short periods of time (usually less than one hour)
b. Network attached storage (NAS) –
computer-based device that provides a large amount of storage to users on a
network
c. Storage area network (SAN) – simpler storage
device and uses network protocols such as iSCSI and Fibre channel to store and
receive data
d. Media converters – used for
converting signals from one medium to another
e. Thin client workstation – a computer
with no disk drives of any kind, often with reduced memory, and some form of
specialized and/or minimalized operating system. Can also be called zero-client workstation
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