Network+ Tables & Charts

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Thanks to Allister for compiling the tables & charts and sharing it with everyone.

[edit section] Tables & Charts

Network topologies

Topology	Description	Advantage	Disadvantage
Star	All nodes connect to a single central device	Inexpensive & easy	If hub fails, network down; maximum nodes = 1024
Bus	All nodes connect to a common backbone	Simple & less cables	If backbone fails, network down; both ends must be terminated
Ring	Each node is connected to two other device	No collisions; less signal degeneration	Expensive; difficult to troubleshoot; proprietary hardware
Mesh	Each node connects to every other device	Redundancy & fault tolerance	Expensive; complicated; difficult to troubleshoot

Common networking standards

Standard	Description	Speed	Access Method	Topology	Media
802.3	Ethernet	10, 100, 1000 Mbps	CSMA/CD	physical star, logical bus	UTP, STP, fiber optics
802.5	Token ring	4, 16 Mbps	Token passing	physical star, logical ring	STP
802.11	Wireless networks	1, 11, 54 Mbps	CSMA/CA	cellular	Atmosphere
FDDI	Fiber Distributed Data Interface	100 Mbps	Token passing	dual ring	Fiber optics

Ethernet specifications

Designation	Cable Type	Max Length	Speed	Connector	Topology	Standard
10BASE-T	Cat3 UTP	100 m	10 Mbps	RJ45	star	IEEE 802.3i
10BASE-FL	MMF	2000 m	10 Mbps	ST	star	IEEE 802.3j
100BASE-TX	Cat5 UTP, Cat5e FTP	100 m	100 Mbps	RJ45	star	IEEE 802.3u
100BASE-FX	Micro MMF	412 m (half duplex) 2000 m (full duplex)	100 Mbps (half duplex) 200 Mbps (full duplex)	SC	star, point-point	IEEE 802.3u
1000BASE-T	Cat5e / Cat6 UTP (4 pairs)	100 m	1 Gbps	RJ45	star	IEEE 802.3ab
1000BASE-CX	Twinax STP	25 m	1 Gbps	HSSDC	star, point-point	IEEE 802.3z
1000BASE-SX	Micro MMF	550 m (50u) 275 m (62.5u)	1 Gbps	SC	point-point	IEEE 802.3z
1000BASE-LX	SMF or MMF	550 m (MMF) 5000 m (SMF)	1 Gbps	SC, LC	point-point	IEEE 802.3z
10 GBASE-SR	MMF	300 m	10 Gbps	850nm serial LAN	point-point	IEEE 802.3ae
10 GBASE-LR	MMF	10,000 m	10 Gbps	1310nm serial LAN	point-point	IEEE 802.3ae
10 GBASE-ER	MMF	40,000 m	10 Gbps	1550nm serial LAN	point-point	IEEE 802.3ae

Wireless networking technologies

Standard	Data Speed	Frequency	Transmission Type	Topology	Range
IEEE 802.11 Legacy	2 Mbps	2.4 GHz	FHSS or DSSS	Point-point	30 m
IEEE 802.11b WiFi	11 Mbps	2.4 GHz	DSSS with CCK	Point-point	30 m
IEEE 802.11a WiFi	54 Mbps	5 GHz	OFDM	Point-point	30 m
IEEE 802.11g WiFi	54 Mbps	2.4 GHz	>20 Mbps: OFDM, <20 Mbps: DSSS with CCK	Point-point	30 m
IEEE 802.11n WiFi	540 Mbps	2.4 GHz	MIMO	Point-point	50 m
Bluetooth	2 Mbps	2.45 GHz	FHSS	Scatternet	10 m
Infrared	100 kbps~ 16 Mbps	100 GHz ~ 1000 THz	Baseband	Point-point LOS	1 m
IEEE 802.16 WiMax	75 Mbps	2 GHz ~ 11 GHz, 66 GHz	BPSK	Point-point Cellular	30 km

The Open Systems Interconnect reference model

No	Layer	Function	Unit	Protocols/Services	Devices
7	Application	network application services and processes	data	FTP, TFTP, HTTP, SMTP, SMB, NCP, Telnet, NTP, File & Print, DNS	gateway
6	Presentation	encryption, formatting, compression, translation	data	ASCII, JPEG, GIF, TIFF, MIDI, MPEG, MIME, Quicktime	gateway
5	Session	establishes maintains, manages network connections and sessions	data	RPC, ZIP, SCP, SQL, NetBIOS, NFS, ASP, LDAP, SSL, SMB	gateway
4	Transport	end-end error recovery, connectivity, flow control	segments	TCP, SPX, UDP, NBP, NCP. NetBEUI, SCTP	gateway
3	Network	routing, forwarding of packets; sequencing of datagram	packets	IP, IPX, ARP, RARP, DHCP, BootP, ICMP, RIP, BGP, OSPF, IPSec	router, brouter
2	Data Link	encoding/decoding of packets into bits; frame synchronization, error checking	frames	MAC, LLC, PPP, ATM, frame relay, 802.11b/g, L2TP, FDDI	switch, bridge
1	Physical	electrical, mechanical, lightwave, radio frequency, media specifications	bits	Ethernet, WiFi, Token Ring, BRI, RS232, V.35	hub, NIC, WAP

Physical media types

Medium	Description	Types	Remarks
Twisted pair	Consists of multiple insulated wires that are twisted together in pairs to prevent crosstalk	UTP, STP, ScTP	Cat3(16MHz), Cat5(100MHz), Cat5e(100MHz), Cat6(250MHz)
Coaxial cable	Consists of a center conductor surrounded by a plastic jacket with braided shield	75Ω, 50Ω	RG-58 (thinnet), RG-8(thicknet), RG-62(ARCnet)
Fiber optic cable	Consists of a center glass core surrounded by glass cladding and other protective materials	SMF , MMF	8~10um(SMF), 50~62.5um(MMF), 125um(clad), EMI immune

Types of media connectors

Connector	Description	Lock Method	Usage	Developed by
RJ11	Registered Jack modular connector (6P2C)	snap-in	telephone equipments, PBX	Bell Telephone Labs
RJ45	Registered Jack modular connector (8P8C)	snap-in	twisted pair ethernet, PoE, ISDN, T1, token ring	Bell Telephone Labs
F-type	F-type coaxial connector (75Ω)	screw-on	broadband cable, CATV, CCTV
BNC	Bayonet Nut Coupling (50Ω)	bayonet	thin ethernet, RF applications	Bell Labs, Amphenol
ST	Straight Tip fiber optic connector	bayonet	fiber optic ethernet	AT&T
SC	Subscriber/Square Connector	snap-in	fiber optic gigabit ethernet	IBM
LC	Local Connector (SFF)	snap-in	fiber optic gigabit ethernet	Lucent
MT-RJ	Mechanical Transfer Registered Jack (SFF)	snap-in	fiber optic ethernet	AMP
IEEE 1394	FireWire (i.Link)	snap-in	digital devices, consumer electronics	Apple, Sony, Samsung, Matshusita, IBM, JVC, …
USB	Universal Serial Bus (1.1 & 2.0)	snap-in	digital devices, computer peripherals	HP, Compaq, Lucent, Microsoft, Intel, NEC, Philips

Network connectivity devices

Device	Purpose	Operation	Remarks
Hub	Connects all nodes in a network together; transmissions received in 1 port are rebroadcast to all ports	Layer 1	concentrator (passive), repeater (active), MAU
Switch	Connects all nodes/segments in a network together; filters and forwards packets; isolate collision domains	Layer 2	multiport bridge, configure VLANs
Bridge	Connects 2 network segments with dissimilar media types; isolate collision domains within a segment	Layer 2	wired or wireless
Router	Connects 2 networks with different topologies; maps nodes & routes packets; isolates broadcast domains	Layer 3	Brouter, IOS
Gateway	Connects 2 networks with different protocols or technologies; could be hardware or software	Layer 4, 5, 6, 7	connection to ISP, PABX
NIC	An expansion card installed in a device to connect/interface to the network; particular to media & protocol	Layer 1, 2	PCI, USB, PCMCIA, built-in M/B
CSU/DSU	A 2 in 1 device used to connect a digital carrier to the network equipment; provides diagnostics & buffering	-	T1, T3; V.35 interface
ISDN adapter	The terminal adapter used to connect to the internet via ISDN technology	-	BRI TA
WAP	A device used to connect mobile PCs to a wired network wirelessly via RF technology	Layer 1, 2	infrastructure mode, WiFi
Modem	A device that changes digital to analog signal and vice versa; modulator/demodulator	-	POTS (V.92), xDSL, cable
Transceiver	A device that transmits or receives analog or digital signals; allows a NIC to connect to a different media type	-	media converter, DIX/AUI
Firewall	A stand-alone device or software used to protect networks from spyware, hackers, worms, phising, trojans	-	port blocking, packet filtering, proxy server, DMZ

Classful IP addressing

Class	Range	Default Subnet	No of Subnets	No of Hosts/Subnet
Class A	1.0.0.0 ~ 126.0.0.0	255.0.0.0	126	16,777,214
Class B	128.0.0.0 ~ 191.0.0.0	255.255.0.0	16,384	65,534
Class C	192.0.0.0 ~ 223.0.0.0	255.255.255.0	2,097,152	254

Reserved IP address blocks

CIDR address block	Description	Reference
0.0.0.0/8	Network or wire address	RFC 1700
10.0.0.0/8	Private network (Class A)	RFC 1918
14.0.0.0/8	Public data network	RFC 1700
39.0.0.0/8	Reserved	RFC 1797
127.0.0.0/8	Localhost (Loop back address)	RFC 1700
128.0.0.0/16	Reserved	-
169.254.0.0/16	Zeroconf , APIPA	RFC 3927
172.16.0.0/12	Private network (Class	RFC 1918
192.0.2.0/24	Documentation and example code	RFC 3330
192.88.99.0/24	IPv6 to Ipv4 relay	RFC 3068
192.168.0.0/16	Private network (Class C)	RFC 1918
198.18.0.0/15	Network benchmark tests	RFC 2544
223.255.255.0/24	Reserved	RFC 3330
224.0.0.0/4	Multicasts (former Class D)	RFC 3171
240.0.0.0/4	Experimental (former Class E)	RFC 1700
255.255.255.255	Broadcast	-

Physical and logical addressing

Version	Length	Notation	Delimiter	Separation	Supports	Example
MAC	48 bits	Hexadecimal	Colon (, Dash (-)	8-bit hexadecimal digits (2 hex)	12x109 combinations	00:50:DA:C3:8A:F9
IPv4	32 bits	Dotted-decimal	Dots (.)	8-bit binary coded decimal digits	4.3x109 addresses	207.142.131.235
IPv6	128 bits	Hexadecimal	Colon (	16-bit hexadecimal digits (4 hex)	3.4x1038 addresses	2001:0DB8:0::0::1428:57AB

Rules of subnetting

No	Rule
1	B bits => 2; R bits => 2
2	Usable subnets created = 2B - 2
3	Usable hosts per subnet = 2R - 2
4	Decimal value of the number of bits borrowed = increment of the subnets

Commonly used well-known ports

Port	Name	Function
20	FTP	Reliable transfer of data; uses TCP
21	FTP	Provides flow control; uses TCP
22	SSH	Executes command and moves files; remote login protocol; uses TCP
23	TELNET	Connects a remote computer to a server; uses TCP
25	SMTP	Delivers emails between email servers; sending of emails; uses TCP
53	DNS	Translates hostnames to IP addresses; uses TCP (zone transfers), UDP (queries)
69	TFTP	Simple transfer of data; uses UDP
80	HTTP	Opens a browser connection to a webpage; uses TCP
110	POP3	Delivers emails between a mail server and client; receiving of emails; uses TCP
119	NNTP	Views and writes news articles for newsgroups; uses TCP
123	NTP	Sets computer clock to standard time; uses UDP
143	IMAP4	Downloads emails; stores and searches messages from newsgroups; receiving of emails; uses TCP
443	HTTPS	Allows browsers and servers to authenticate and encrypt network packets; uses SSL; uses TCP

Switching type comparison

Resource	Circuit Switching	Packet Switching
Dedicated path?	yes	no
Available bandwidth?	fixed	dynamic
Could Bandwidth be wasted?	yes	no
Store-and-forward transmission	no	yes
Each packet follows the same route?	yes	no
Call setup	required	not required
When can congestion occurs?	at set-up	at every packet
Charge?	per minute	per packet

Network protocols

Protocol	Routing	Addressing	Naming	Interoperability
IPX/SPX	RIP, SAP, NLSP	12-digit hexadecimal	server names only: 64 characters, no special characters; NDS	Windows, Linux
NetBEUI	unroutable	-	NetBIOS or computer names; WINS	Windows
AppleTalk	version1: unroutable; version2: RTMP	24-bit address	version1: NBP; version2: IP naming	ethernet: ELAP, token ring: token talk
TCP/IP	RIP, OSPF	32-bit address	DNS, ARP, RARP	Windows, UNIX, Linux, Mac, Novell

Digital transmission hierarchies

Carrier	Channels	Data Rate	Format
T1	24	1.544 Mbps	North American
T3	672	44.736 Mbps
E1	32	2.048 Mbps	European
E3	480	34.368 Mbps
J1	24	1.544 Mbps	Japanese
J3	480	32.064 Mbps

Optical carriers

Level	Data Rate
OC-1	51.84 Mbps
OC-3	155.52 Mbps
OC-12	622.08 Mbps
OC-24	1.244 Gbps
OC-48	2.488 Gbps

xDSL technologies

Type	Distance	Downstream	Upstream	Characteristic Use
ADSL	18,000 ft	1.544 Mbps ~ 6.1 Mbps	126 kbps ~ 640 kbps	Most popular; used for web access and multimedia streaming
SDSL	12,000 ft	1.544 Mbps(US), 2.048 Mbps(EU)	1.544 Mbps(US), 2.048 Mbps(EU)	WAN connection from company network server to phone company
HDSL	12,000 ft	1.544 Mbps (2p), 2.05 Mbps (3p)	1.544 Mbps (2p), 2.05 Mbps (3p)	WAN connection from company network server to phone company
IDSL	18,000 ft	128 kbps	128 kbps	Transmits data only; similar to ISDN BRI
CDSL	18,000 ft	1.544 Mbps	<1.544 Mbps	Used in home and small business; no splitter; known as G.lite
RADSL	n/a	640 kbps ~ 2.2 Mbps	270 kbps ~ 1.1 Mbps	Same as ADSL
VDSL	4500 ft	1.6 Mbps ~ 53 Mbps	1.5 Mbps ~ 2.3 Mbps	ATM networks using fiber optic cable

TCP/IP protocol suite

Name	Meaning	Function
TCP	Transmission Control Protocol	Enables two hosts to establish connection and exchange network data; connection-oriented; guaranteed delivery of packets
UDP	User Datagram Protocol	Enables two hosts to establish connection and exchange network data; connectionless, unreliable, less overhead
FTP	File Transfer Protocol	Downloads or uploads files between hosts; performs directory operations; also offers authentication security
SFTP	Secure File Transfer Protocol	Transfer of files with SSH to provide encryption, public key authentication, and file compression; similar to FTP
TFTP	Trivial File Transfer Protocol	Facilitates file transfer between computers; uses lesser bandwidth and faster speed; similar to FTP; used in firmware downloading
HTTP	HyperText Transfer Protocol	Transfer files or web pages from web server to client web browser; uses lesser bandwidth and supports both text and graphics
HTTPS	HyperText Transfer Protocol Secure	Allows browsers and servers to authenticate and encrypt network packets using SSL; secure version of HTTP
SMTP	Simple Mail Transfer Protocol	Uses a spooled or queued method to deliver or send emails
POP3	Post Office Protocol version 3	Used to retrieve email files from the email server; can be used with or without SMTP
IMAP4	Internet Message Access Protocol version 4	Used to retrieve email files from the email server; similar to POP3 but with added features; supports Kerberos
Telnet	Telephone Network	A terminal emulation program that connects remote computers to a server; execute a commands using command prompt
SSH	Secure Shell	A suite of protocols used to log into another computer on the network, execute commands, and secure transfer of files
ICMP	Internet Control Message Protocol	Provides network layer management and control by sending datagrams and control messages; works with IP
ARP	Address Resolution Protocol	Resolves network addresses (IP) into hardware addresses (MAC); uses address resolution cache table built into every NIC
RARP	Reverse Address Resolution Protocol	Uses host MAC address to discover its IP address
NTP	Network Time Protocol	Sets computer clock to a standard time source usually a nuclear clock
NNTP	Network News Transfer Protocol	Used for the distribution, inquiry, retrieval, and posting of news articles and newsgroup forum messages
SCP	Secure Copy Protocol	Safe and secure copying of files between a local and remote computer; similar to SFTP
LDAP	Lightweight Directory Access Protocol	A session layer protocol that provides directory services and access to x.500 information directories
IGMP	Internet Group Multicast Protocol	A network layer protocol used to report multicast group membership to adjacent routers
LPR	Line Printer Remote	A printer protocol used to print across different NOS platforms

Network services and protocols

Name	Meaning	Function
DNS	Domain Name System	Translates and resolves IP addresses into host names or the reverse
DHCP	Dynamic Host Configuration Protocol	Allows a client device to request and obtain a unique IP address and other parameters from a server automatically
NAT	Network Address Translation	Allows a local network to use one set of IP address for internal or in-house traffic and a different set for external or internet traffic
ICS	Internet Connection Sharing	Connects multiple computers on a local network to the internet through a single connection and IP address; uses NAT
WINS	Windows Internet Naming Service	Resolves a host NetBIOS name or computer name into an IP address; used in legacy Windows
SNMP	Simple Network Management Protocol	Monitors the network and network devices; sends messages to different parts of the network; uses MIB
NFS	Network File System	Permits network users to access and used shared files; allows different computer platforms to share files and disk space
Zeroconf	Zero Configuration	Connects networking devices using an Ethernet cable; no configuration or DHCP required
SMB	Server Message Block	Shares files, directories, and services; message format used by DOS; allows UNIX/Linux and Windows machines to share files
AFP	Appletalk File Protocol	A file sharing protocol used with TCP/IP to permit non-apple computers to access apple servers
LPD	Line Printer Daemon	Processes LPR print jobs, queues, and prints files
Samba	-	Provides file and print services to SMB clients; runs on UNIX and Linux
ICA	Independent Computing Architecture	The core of Citrix presentation server that enables Windows or UNIX server to run an application for multiple users simultaneously
Apache	-	A popular public domain UNIX-based web server

Remote access protocols and services

Name	Meaning	Function
RAS	Remote Access Service	Used for client remote access to a network
PPP	Point-Point Protocol	Used to establish an internet connection between serial point-to-point links; provides for dial-up connnections to networks
SLIP	Serial Line Internet Protocol	Used to connect to the internet via a dial-up modem; older, slower, less reliable than PPP
PPPoE	PPP over Ethernet	Uses PPP over Ethernet to connect an ethernet LAN user to the internet using an ADSL or cable modem; users share a broadband connection
PPTP	Point-Point Tunnel Protocol	A form of encryption that provides a tunnel for secure connections over the internet; used to create VPN
VPN	Virtual Private Network	A private, secure, point to point connection from a company LAN to the remote users and wireless nodes using the internet
RDP	Remote Desktop Protocol	connects a client to a network via a terminal server and uses authentication to establish connection to run applications and printers remotely

Security protocols

Name	Meaning	Function
IPSec	Internet Protocol Security	Provides authentication and encryption over the internet; works with IPv4 and IPv6; used to secure VPN
L2TP	Layer 2 Tunneling Protocol	Supports non-TCP/IP protocols VPN over the internet; combines the best features of PPTP and L2F
SSL	Secure Sockets Layer	Uses a private key to encrypt data that is transferred over the SSL connection; service independent and can secure different network applications
WEP	Wired Equivalent Privacy	Encrypts and protects data packets over radio frequencies; does not offer end-end security
WPA	WiFi Protected Access	Offers improved data encryption and user authentication using the wireless devices MAC address; uses TKIP encryption
AES	Advanced Encryption Standard	A cryptographic cipher that uses Rijndael algorithm
PGP	Pretty Good Privacy	An encryption utility based on public key encryption designed to encrypt email transmissions
802.1x	-	Method for passing EAP over both wired and wireless networks; provides authentication services for wireless networks not using PPP

Authentication protocols

Name		Function
CHAP	Challenge Handshake Authentication Protocol	Uses a hashed algorithm MD5 that provides client response encryption; weak and one-way authentication protocol
MS-CHAP	Microsoft Challenge Handshake Authentication Protocol	Has two versions used in Windows systems that offers more security; version1 not compatible with version2
PAP	Password Authentication Protocol	The weakest authentication protocol that sends username and password in clear text over the network to be verified by RAS
RADIUS	Remote Authentication Dial-in User Service	An industry standard that provides authentication, authorization, and accounting services
Kerberos	-	A fully-fledge security system that uses secret key cryptography
EAP	Extensible Authentication Protocol	A general protocol often used by a wireless devices to connect to a RADIUS server; TLS uses certificates such as smart cards

Routing protocols

Name	Meaning	Function
RIP	Routing Information Protocol	Finds the quickest route between two computers; offers a maximum of 16 hops between routers before deciding that a packet is undeliverable
OSPF	Open Shortest Path First	A descendant of RIP that increases its speed and reliability; much used on the internet; accepts 256 hops between routers
IGRP	Interior Gateway Routing Protocol	A propriety protocol from Cisco that takes bandwidth, latency, reliability, and current traffic load into consideration
EGP	Exterior Gateway Protocol	A distance vector protocol that uses polling to retrieve routing information
BGP	Border Gateway Protocol	Used to span autonomous systems in the internet; used at the edge of networks; designed to supersede EGP
NLSP	Netware Link Services Protocol	A link state routing protocol that was designed to reduce wasted bandwidth associated with RIP
RTMP	Routing Table Maintenance Protocol	Used by Appletalk to ensure that all routers in the network have consistent routing information

Network operating system versions

Vendor	Releases
Novell	Netware 3.x, 4.x, 5.x, 6.x
Microsoft	Windows NT, Windows 2000, Windows Server 2003
Apple	Mac OS X, AppleShare IP
UNIX/Linux	SCO ACE, RedHat

Server operating systems basic capabilities

Operating System	Client Support	Authentication	File & Print Services	Interoperability
UNIX/Linux	multi-user, multitasking; GUI	etc/password; NIS authentication; LDAP	LPD/LPR; FAT16, FAT32, NTFS, Ext2, Ext3; NFS	Windows, Linux, Netware, Mac OS
Netware	multi-user, multitasking; GUI	user password; keys stored in NDS; eDirectory	FAT16, FAT32, NTFS, NFS, AppleShare	Windows, Linux, Netware, Mac OS
Windows	multi-user, multitasking; GUI	domain username/password; AD	LPD/LPR; FAT16, FAT32, NTFS	Windows, Linux, Netware, Mac OS
Mac OS	multi-user, multitasking; GUI	kerberos mechanism; keychain; OD	UNIX-type file system, AppleShare IP	Windows, Linux, Netware, Mac OS

TCP/IP utilities

Utility	Operating System	Function	Switches
config	NetWare	displays IP stack configuration
ifconfig	UNIX/Linux	displays IP stack configuration
winipcfg	Windows 95/98	displays IP stack configuration
ipconfig	Windows NT/2000/XP	displays IP stack configuration, release/renew DHCP IP address, flush/register DNS	/all /renew /release /flushdns /registerdns
ping	Windows/UNIX/Linux/Netware	verifies end-to-end network connectivity; uses ICMP echo packets	–t –a –n –l –f –i –r –v
tracert	Windows 2000/XP/2003	traces routes to internet sites based on the number of hops and displays time taken	–d –h –j –w
traceroute	UNIX/Linux	traces routes to internet sites based on the number of hops and displays time taken
netstat	Windows/UNIX/Linux/Netware	displays protocol statistics and current TCP/IP network connections	–a –b –e –r –o –s –n –p
nbtstat	Windows/UNIX/Linux/Netware	displays protocol statistics and current TCP/IP network connections using NetBIOS over TCP/IP	–a –A –c –n –r –R –S –s
arp	Windows/UNIX/Linux/Netware	displays and/or modifies IP to physical address translation tables; displays current ARP cache	–a –g –s –N
nslookup	Windows 2000/XP/2003	queries a DNS name server; used to troubleshoot DNS and verify DNS resolution	–a –d –t exit
dig	UNIX/Linux	nslookup equivalent
telnet	Windows/UNIX/Linux/Netware	enables a computer to function as a terminal working from a remote computer	–a –e –f –l –t
netuse	Windows NT/2000/XP	used to connect to file or print share

Tools for network cabling and troubleshooting

Tool	Usage
Wire crimper	Used to affix an UTP/STP cable to a modular connector or plug
Punchdown tool	Used to affix several cables to a punchdown block or a patch panel found in wiring cabinets
Media tester/certifier	Used to test continuity or polarity of cables, trace shorts along the line; can’t be used on live/active wires
Tone generator	Used along with a probe to verify cable continuity, identify wiring faults, determine line voltage and polarity; can be used in active wires

Common network implementation

Implementation	Purpose	Characteristics/Benefits	Remarks
Firewall	security	Permits/denies public traffic based on various filtering rules; protection from internet threats	ACL, DMZ
Proxy server	security, performance	A firewall method that caches web content for improved network performance; establish VPN for remote users	web proxy, ip proxy
Antivirus software	security, maintenance	Software used to search/remove malicious programs on network computer hard drives; prevents infection	viruses, worms, trojan horses
VLAN	security, performance	Better bandwidth management; reduced administration costs; well-defined groups; improved network security	static/dynamic; VTP, DTP
Intranet	cost, flexibility	A private network based on TCP/IP which resides behind a firewall; cheaper, versatile, flexible information sharing	-
Extranet	security, versatility	Extension of a corporate intranet; exchange data between suppliers/customers; secure corporate purchasing	-
Clustering	fault-tolerance, load balancing	A group of redundant mirrored servers; high availability and scalability; minimized network downtime	-

Network security implementation

Implementation	Purpose	Impact on network	Remarks
Port blocking	intrusion detection	slows down	firewalls, proxy servers
Packet filtering	intrusion detection	slows down	firewalls, proxy servers
Authentication	access control	none	NOS logon server
Encryption	data protection	slows down	IPSec, PKI, PGP, Kerberos, DES

Characteristics of fault-tolerance

Item	Implementation
Power	UPS, SPS; backup generators, cooling fans, processors; surge suppressor; line conditioners
Link redundancy	Backup links: ISDN, dial-up; microwave wireless radios; secondary ISP; clustering
Storage	Hardware or software RAID; SCSI hard disks; data warehousing
Services	Mission critical servers and equipments: gateways, routers, switches; SAN clusters, MSOS
Disaster recovery	Backup/restore schemes; offsite storage: NAS, SAN; hot/cold spares; hot, warm, cold sites

Types of RAID

Level	No of drives	Description
RAID 0	2	disk stripping without fault tolerance
RAID 1	2	disk mirroring/duplexing
RAID 0+1	4	a mirror of stipes
RAID 5	3	stripping with parity
RAID 10	4	stripe of mirrors

Backup types

Type	Description	Clears archive bit?	Sets to restore
full/normal	backs up all data; longest time to backup	Y	full only
incremental	backs up files changed or added since the last backup; faster to backup; uses more tapes	Y	full + every incremental
differential	backs up files changed or added since the last full backup; faster to restore; uses lesser tapes	N	full + last differential
mirror/copy	backs up all data; used to make offsite copies;	N	-

Types of backup tape drives

Drive	Description	Capacity	Data Transfer Speed
QIC	Quarter Inch Cartridge; formats: 3.5", 5.25"	20 GB, 50 GB	60 kbps, 125 kbps
Travan	Enhancement of QIC; formats: TR4, TR5	4/8 GB, 10/20 GB	1 Mbps, 1.83 Mbps
DAT	Digital Audio Tape; formats: DDS (Digital Data Storage), DLT (Digital Linear Tape)	40 GB (DDS), 160 GB (DLT)	4.8 Mbps, 20 Mbps
Mammoth	An 8mm backup format used in computer systems; AIT (Advanced Intelligent Tape)	10/20 GB, 20/40 GB	3 Mbps, 6 Mbps

Troubleshooting strategy

No	Step
1	Identify the symptoms
2	Identify the affected area
3	Establish what has changed
4	Select the most probable cause
5	Implement a solution and action plan
6	Test the result
7	Recognize the effects of the solution
8	Document the solution and process

IEEE Standards

Standard	Description
802.1	Internetworking
802.2	Logical Link Control (LLC)
802.3	Ethernet (CSMA/CD)
802.4	Token bus LAN
802.5	Token ring LAN
802.6	Metropolitan Area Network (MAN)
802.7	Broadband technical advisory
802.8	Fiber optic
802.9	Integrated voice/data
802.10	Network Security
802.11	Wireless Networks
802.12	Demand Priority (100VG-Any LAN)
802.13	Not used
802.14	Cable modem
802.15	Wireless personal area network
802.16	Broadband wireless access
802.17	Resilient packet ring