Networking Plus 2005 Notes 1. Standard Topologies

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1

Networking Plus
2005 Notes

1. Standard Topologies

Bus

-

A single cable (trunk) that connects all computers in a single line.

Star

-

Computers connect to a centralized hub via cable segments.

Ring

-

Connects all computers on a single cable. Ends are n
ot terminated, but form a full

Mesh

-

Commonly used in WAN configurations. Routers are connected to multiple links for redundancy and to
give the ability to determine the quickest route to a destination.


2. Access Methods

Accessing Network Media

Token

Ring


Deterministic access method

Ethernet


Contention based method

CSMA/CD

-

Collision Detection; listens to cable prior to sending data. (Ethernet)

CSMA/CA

-

Collision Avoidance; Announces intention to send data. (AppleTalk)

Token
-
Passing

-

Token r
evolves around ring, computer which has token is permitted to data. (Token Ring)

One device designated media administrator. Secondary device waits to be polled by primary device to check if it
has data to be sent.


3. IBM Cabling System


RG stands for Rad
io Guide

Thinnet Coaxial
-

.25 inches thick carries signal 185 meters. Known as RG
-
58 family and has a 50 ohm
impedance.

RG
-
58 /U

-

Solid Copper Core

RG
-
58 A/U

-

Stranded Wire Core

RG
-
58 C/U

-

Military Specification of RG
-
58 A/U

RG
-
59


-

Broadband
transmission (Television Cable)

RG
-
62


-

ArcNet Network Cable

-

When troubleshooting thinnet coaxial cable, the cable terminator must read 50 ohms, and the cable and
connector must measure infinite.

Thicknet Coaxial


-

.5 inches thick, carries signal 50
0 meters. A transceiver (Vampire Tap) is used to
make a physical connection with the Thicknet core.

Unshielded Twisted Pair
-

Twisted pair wiring, carries signal 100 meters. Is susceptible to crosstalk.

Shielded Twisted Pair


-

Twisted pair wiring, carri
es signal 100 meters. Has foil or braided jacket around wiring
to help reduce crosstalk and to prevent electromagnetic interference.

Attenuation

-

The degrading of a signal as it travels farther from its origination.

Crosstalk

-

Signal overflow from on
e wire to another adjacent wire.

Jitter


-

Instability in a signal wave. Caused by signal interference or an unbalanced FDDI ring or
Token Ring.


4. UTP/STP Category Speeds

Cat 2

-

4 mbps

Cat 3

-

10 mbps

Cat 4

-

16 mbps

Cat 5

-

100 mbps

Fiber
-
O
ptic
-

Carries light pulse signals through glass core at speeds of between 100 Mbps
-

200,000 Mbps.


5. Ethernet Specifications

Type



Cable types



Connection Type

Max Length

10Base2


-

RG
-
58 thinnet coaxial cable

BNC T Connector

185 meters (607 f
t)

10Base5


-

Thicknet coaxial cable


DIX/AUI


500 meters (1640 ft)

10BaseT


-

Category 3, 4, or 5 UTP cable

RJ
-
45



100 meters (328 ft)

100BaseT


-

Category 5 UTP cable


RJ
-
45



100 meters (328 ft)


6. Signal Transmissions

Baseband

-

Uses di
gital signaling over a single frequency. Transmits bi
-
directionally.

Broadband

-

Uses analog signaling over a range of frequencies. Transmits unidirectionally and uses
amplifiers for signal regeneration.



2

7. OSI Model

Application Layer

-

Allows appl
ications to use the network. Handles network access, flow control and error
recovery.

Presentation Layer

-

Translates data into a form usable by the application layer. The redirector operates
here. Responsible for protocol conversion, translating and enc
rypting data, and managing data compression.

Session Layer

-

Allows applications on connecting systems to establish a session. Provides synchronization
between communicating computers.

Transport Layer

-

Responsible for packet handling. Ensures error
-
fr
ee delivery. Repackages messages
into smaller packets, and handles error handling.

Network Layer


-

Translates system names into addresses. Responsible for addressing, determining
routes for sending, managing network traffic problems, packet switching, r
outing, data congestion, and
reassembling data.

Data Link Layer

-

Sends data from network layer to physical layer. Manages physical layer
communications between connecting systems.


LLC

-

(802.2) Manages link control and defines SAP's (Service Access P
oints). Checks ACK, CRC


MAC

-

(802.3, 802.4, 802.5, 802.12) Communicates with adapter card. Responsible for Carrier Sense
and Token Passing

Physical Layer

-

Transmits data over a physical medium. Defines cables, cards, and physical aspects.


7a.
OSI la
yer

Protocols residing here

Application

SMB, NCP

Presentation

NCP

Session



None

Transport

TCP, SPX, NWLink, NetBEUI

Network

I
P, IPX, NetBEUI, DLC, DecNET

Data Link

None

Physical

None


8.
IEEE 802 Specifications

802.1

Internetworking

802.2

LLC (
Logical Link Control)

802.3

CSMA/CD
-

Ethernet

802.4

Token Bus LAN

802.5

Token Ring LAN

802.6

MAN (Metropolitan Area Network)

802.7

Broadband Technical Advisory Group

802.8

Fiber
-
Optic Technical Advisory Group

802.9

Integrated Voice/Data Netwo
rks

802.10

Network Security

802.11

Wireless Networks

802.12

Demand Priority Access LAN, 100 Base VG
-

AnyLAN


8
a
. LAN Enhancement Components

Repeater

-

regenerates signals for retransmission. Moves packets from one physical media to another.
Will

pass broadcast storms. Cannot connect different network topologies or access methods.

Bridges

-

are used to segment networks. They forward packets based on address of destination node.
Uses RAM to build a routing table based on hardware addresses. Will
connect dissimilar network topologies.
Will forward all protocols. Regenerates the signal at the packet level.

Routers

-

packets across multiple networks. Uses RAM to build a routing table based on network
addresses (i.e. TCP address). Shares status and
routing information to other routers to provide better traffic
management and bypass slow connections. Will not pass broadcast traffic. Are slower than bridges due to
complex functions. Strips off Data Link Layer source and destination addresses and then r
ecreates them for
packets. Routers can accommodate multiple active paths between LAN segments. Will not pass unroutable
protocols.

Brouter

-

Will act as a router for specified protocols and as a bridge for other specified protocols.

Gateway

-

Used for

communications between different NOS's (i.e. Windows NT and IBM SNA). Takes
the packet, strips off the old protocol and repackages it for the receiving network.
Basically converts data
between incompatible sstems for different networks.


3

Multiplexer Device

-

that can divide transmissions into two or more channels.

Switches

-

Hub with bridging capabilities. Switch filters traffic through MAC addresses. Creates sessions
on ports within the hub. Used when upgrading to 100mb Fast Ethernet.

Repeater

Physical


Bridge



Data Link (MAC Sublayer)

Remote Bridge Data Link (MAC Sublayer)

Router



Network

Brouter



Data Link and Network

Gateway

Transport, Session, Presentation and Application

Multiplexer

Physical

Switch



Data Link

Spanning Tree Algorithm
-

was developed for bridges to determine the most efficient network in path when there
are multiple paths to choose from.

Multiplexing
-

Several signals from different sources are collected into the component and are fed into one cable
for transmission.


8
b
. Protocols

Routable

-

TCP/IP, IPX/SPX, OSI, AppleTalk, DecNET, XNS. Non
-
routable
-

NetBEUI, DLC

NetBEUI

-

Microsoft protocol designed for small LANs; non
-
routable. Not compatible with UNIX networks.

IPX/SPX

-

Fast protocol for small and large Novell
networks; is routable. Also known in NT as NWLink.

TCP/IP


-

Internet protocol; is routable. Used by UNIX networks. Remember IP is connectionless

DecNET

-

Defines communications over FDDI MANs; is routable.

AppleTalk

-

Apple protocol designed for sma
ll LAN file and print sharing; is routable.

RIP (Routing Information Protocol)
-

Routers use this to communicate with each other to determine the least
busy and shortest network routes.

NDIS (Microsoft) and ODI (Novell) are used to bind multiple protocol
s to a network adapter.

SLIP (Serial Line IP)

-

Provides dial
-
up communications, but is unable to simultaneously transfer multiple
protocols.

PPP (Point
-
to
-
Point Protocol)
-

Performs dynamic IP addressing, multi
-
protocol support, password login and
error

control.

Common TCP/IP problems are caused by incorrect subnet masks and default gateways.

Incorrect frame types will cause problems between two systems using IPX/SPX.


8
c.

Protocols within TCP/IP

FTP



File Transfer


connection oriented

TFTP



is conn
ectionless

SMTP



Simple Mail Transfer Proto

HTTP



this is a “stateless” protocol meaning each command is executed independently

POP3



Remember

it is mail delivery ONLY


it does not handle sending messages. Port 110

Telnet



port 23

ICMP



control
, uses PING

DNS



port 5
3

DHCP



need to allow DHCP relay agents in order to send broadcasts over routers (which by design do not
normally accept ANY broadcasts). Basically DHCP is a form of broadcast Remember DORA which stands for
the lease process and
menas Discover, Offer, Request, ACK NOTE: DHCP uses ARP to assign IP addresses to
clients

SNMP



Simple Network Management Protocol
consists of two components, an agent and SNMP mgmt
console (according to a MIB). Uses READ, WRITE, TAVERSAL and TRAP comma
nds. These are set up with
GET requests (GET is actually a READ command)Most common way of security in SNMP is community names.
Port 161 and 162

Consists of three elements:


1. SNMP Mgmt Console (OpenView, Tivoli, etc)


2. Agent


3. MIB



4

9. Computer Name
Resolution

DNS (Domain Name Services)
-

Used to translate a host name to an IP address. Default gateways and sbnets
can also be assigned by DNS. Remember that FQDN is fully qualified domain

WINS (Windows Internet Naming Service)
-

Used to resolve NetBIOS
computer name to an IP address. Similari
to DNS except that it only works on a Microsoft network. WINS can be combined with DNS. WINS has both a
server and a client component

HOSTS
-

File which contains mappings between DNS host names and their IP addresse
s.

LMHOSTS
-

File which contains mappings between NetBIOS computer names and their IP addresses.

Packet Switching
-

Packets are relayed across network along the best route available.

Beaconing
-

Computers are used to detect network faults, then transmit

the fault signal to the server.

Packet Switching Networks



(sent in burst over the network in asynchronus


meaning not in any order). QoS is nearly non
-
existent versus
circuit switched

Type


Function

X.25


Designed to connect remote terminals to mainf
rame host systems. Is very slow due to constant
error
-
checking.

Frame Relay

Point
-
to
-
point system which uses digital leased lines. Will provide bandwidth as needed.
Requires frame relay capable bridge or router for transmission. Frame is roughly equivalent

to ISDN in
performance. This is a connectionless service

ATM


OPERATES AT DATA LINK LAYER and is connection
-
oriented Advanced implementation of
packet switching. Asynchronus Transfer Mode. Transmits at speeds of 155Mbps to 622Mbps with capabilities of
hig
her speeds. Transmits data in 53 byte (48 application, 5 header) cells. Uses switches as multiplexers to
permit several computers to simultaneously transmit data on a network. Great for voice and video
communications. ATM can prioritize data

ISDN


Transmi
ts at 128k/sec. Has three data channels
-

2 B channels @ 64k/sec & 1 D channel @
16k/sec. The B channels carry data while the D channel performs link management and signaling. PRI is
roughly equivalent to T
-
1 One D channel and 23 B channels

FDDI


100 Mbps
token
-
passing ring network which uses fiber
-
optic media. Uses a dual
-
ring topology
for redundancy and in case of ring failure. Each ring is capable of connecting 500 computers over 100
kilometers (62 miles). Can be used as a network backbone. Uses beaconin
g for ring troubleshooting.


Cable and DSL

Cable modems are not really modems at all. They use coax cable. DSL has a max distance of
18,000ft with the most popular flavor of DSL bing ADSL

Circuit
-
Switching Networks
u
se ONE consistent circuit. Can be either

a physical circuit or a virtual circuit. ISDN
is a virtual circuit

The communication is usually a DEDICATED circuit.


10. Network Diagnostic Tools

Tool




Function

Digital Volt Meters (DVM)

Measures voltage passing through a resistance
. Primarily used for network
cable troubleshooting.

Time
-
Domain Reflectors (TDRs)

Sends sonar
-
like pulses to look for breaks, shorts or crimps in cables. Can
locate a break within a few feet of actual fault.

Oscilloscope




Measures amount of sig
nal voltage per unit of time. Displays crimps, shorts,
opens, etc.

Network Monitor


Examines packet types, errors and traffic to and from each computer on a
network.

Protocol Analyzer



Look inside the packet to determine cause of problem. Contains built

in Time
-
Domain Port Scanner


Scans for open TCP/UDP ports


11.

Multiple Disk Sets

Fault Tolerant Systems protect data by duplicating data or by placing data in different physical sources.

RAID


Function

Level 0


Disk Striping
-
Divides data into 64k blo
cks and spreads it equally among all disks in the array. Is
not fault tolerant.

Level 1


Disk Mirroring

-
Duplicates a partition on another physical disk.

Level 1


Disk Duplexing

-
Duplicates a partition on another physical disk that is connected to anothe
r
Hard Drive Controller.


5

Level 2


Disk Striping w/ECC

-
Data blocks are broken up and distributed across all drives in array
with error checking.

Level 3


Disk Striping w/ ECC stored as parity
-
Data blocks are broken up and distributed across all
drive
s in array with one drive dedicated to storing parity data.

Level 4


Disk Striping with large blocks

-
Complete blocks of data are distributed across all drives in the
array.

Level 5


Disk Striping with parity

-
Distributes data and parity information acr
oss all disks in the array.
The data and the
p
arity information are arranged so they are always on separate disks. A parity stripe block
exists for each row across the disk. The parity stripe is used for disk reconstru
ction in case of a failed disk.



Suppor
ts a minimum of three disks and a maximum of thirty
-
two disks.



Windows NT supports RAID Levels 0, 1, and 5.



Sector Sparing
-

Automatically adds sector
-
recovery capabilities to the files system while the computer
is running. Available when using RAID method
s. Only available with SCSI drives.


12. Upgrading the network
.

To upgrade a network to 100 mbps Ethernet, you must perform the following:

-

Upgrade all hubs to switches or 100 mbps hubs.

-

Upgrade the wiring to CAT 5 UTP/STP.

-

Upgrade all network c
ards to 100 mbps.


13. Reliable Packet Delivery

Methods and Checks

-

Parity Checks


you add an additional BIT to both ends

-

CRC (Cyclical Redundancy Check)

-

EDAC


Error Detection and Correction

-

EXAM Tip
SQUELCH


is the signal sent by recvg n
ode to slow down transmission of data from sender


14. TCP Command Line Utilities

arp
-

Arp.exe is used to resolve an IP address to its hardware (MAC address). Local Arp cache is checked first
before initiating an ARP request broadcast

arp s
witches

-
a
-

View the contents of the local ARP cache table

-
s
-

Add a static Arp entry for frequent accessed hosts

-
d
-

Delete a entry

ipconfig
-

The ipconfig is a command line tool for NT that shows how the computer's IP stack is
configured.C:
\
ipconfig

ipconfig s
w
itches

/all
-

Extra information is revealed; IP host name, DNS, WINS server

/release
-

If DHCP is enabled, you release the lease with this switch.

/renew
-

The renew switch will update and renew DHCP lease information from the DHCP Server.

w
inipcfg
-

The w
inipcfg is a GUI version for ipconfig

n
etstat
-

The netstat tool displays protocol statistics and the state of current TCP/IP connections

C:
\
WINDOWS>netstat /?

Displays protocol statistics and current TCP/IP network connections.

netstat

[
-
a] [
-
e] [
-
n] [
-
s] [
-
p proto] [
-
r] [interval]


-
a Displays all connections and listening ports.


-
e Displays Ethernet statistics. This may be combined with the
-
s


option.


-
n Displays addresses and port numbers in numeri
cal form.


-
p proto Shows connections for the protocol specified by proto; proto may be TCP or UDP. If used with the
-
s option to display per
-
protocol statistics, proto may be TCP, UDP, or IP.


-
r Displays the routing table.


-
s



Displays per
-
protocol statistics. By default, statistics are

s
hown for TCP, UDP and IP; the
-
p option
may be used to specify a subset of the default.


interval Redisplays selected statistics, pausing interval seconds between each display. Press CTRL
+C to
stop redisplaying statistics. If omitted, netstat will print the current

configuration information once.


nbtstat The nbtstat checks the state of NetBIOS over TCP/IP connections and returns NetBIOS session and
name resolution statistics. This tool c
an also be used to update the local NetBIOS name cache.

Displays protocol statistics and current TCP/IP connections using NBT(NetBIOS over TCP/IP).


6

nbtstat

[
-
a RemoteName] [
-
A IP address] [
-
c] [
-
n] [
-
r] [
-
R] [
-
s] [S] [interval] ]


-
a (adapter status)

Lists the remote machine's name table given its name


-
A (Adapter status)

Lists the remote machine's name table given its IP address.


-
c (cache)

Lists the remote name cache including the IP addresses


-
n (names)

Lists local N
etBIOS names.


-
r (resolved)

Lists names resolved by broadcast and via WINS


-
R (Reload)

Purges and reloads the remote cache name table


-
S (Sessions)

Lists sessions table with the destination IP addresses


-
s (sessions)


Lists sessions table converting destination IP addresses to host names via the hosts
file.


RemoteName

Remote host machine name.


IP address



Dotted decimal representation of the IP address.


interval



Redisplays selected statistics, p
ausing interval seconds between each display.

Press Ctrl+C to stop redisplaying statistics.

Note: Netstat works for TCP/IP connections, and Nbtstat works for NetBIOS connections.



nslookup The Nslookup tool is used to trace DNS queries from start to fini
sh


p
ing
-

Ping.exe verifies configurations and tests connectivity
If you can ping a hostname but cannot connect to a
share point in Explorer, then the LMHOST file does not have an entry
for that hostname or WINS is not working.
Conversely, if you CAN connect to a share in Explorer yet cannot ping the hostname, then either the HOST file
entry is wrong or DNS is not working.

NetBIOS
-
problems are due to problems with WINS or LMHOST file.

D
NS
-

problems are due to HOST file errors or DNS server problems.


Tracert
-

The tracert tool shows the route a packet will take over a network from one computer to another.


15. Port

Number
s

Number Description


Number Description

2
1


FTP




69



TFTP

23


Telnet




80


HTTP

25


SMTP




110


POP

53


DNS



137


WINS

161


SNMP



389


LDAP

1494


Citrix



22


SSH

123


NTP(network time prot) 1723


PPTP (Microsoft VPN)

443 HTTPS

143 IMAP4


16. Address Classes:

Decimal



Binary

Class A:1
-
126


00000001
-
01111111

Class B:128
-
191

10000000
-
10111111

Class C:192
-
223

11000000
-
11011111

Class D:224
-
239

11100000
-
11101111

Class E:240
-
255

11110000
-
11111111


The 1
27.0.0.0 network is reserved for “loopback” testing of the TCP/IP Stack within your system.

Class D is used for Multicast

Class E is reserved for experimental purposes


17. Routing Algorithms

Distance Vector



aka “Gossiping”

RIP, IGRP
, EIGRP

Only allows f
or up to 15 routers in a network

Transfers its entire table to its neighbors


translates the WHOLE table

IGRP


adds 6 diff metrics over RIP

EIGRP
-

supports VLSM


7

Link State

IS
-
IS, OSPF


a. Larger metrics


b. Allows for thousands of routers (actually 65,5
35)


c. “Helo” packerts every 30 seconds


d. Rapds convergence


18. Data Link Protocols for Point to Point Links

SLIP (Serial Line IP)


Support ONLY IP (not IPX)

Encapsulation


not much else

PPP (Point to Point Protocol)


has error detection


SLIP doe
s NOT

Successor to SLIP. Uses a serial connection

Used for dial
-
in and high speed routers

HDLC (High Level Data Link)

Default protocol for serical links on Cisco routers

NAT

NAT is a router function which enables hosts on a private network to communicate w
ith hosts on internet. Used
for pooling of addresses. The “duh” of it all says that it connects multiple computers to other IP networks using
only ONE single IP address.


5:4:3 Law

5 segments, 4 repeaters and 3 nodes


Default Gateway

has t
hree elements:



IP

address



Sugnet Mask



Default gateway itself


Troubleshooting


Always REMEMBER: “If it’s broke, it’s probably DNS”


19. Firewalls

Packet
-
filtering firewalls (transparent , cost
-
effective, no user authentication

application based firewalls (clients do not c
onnect directly to outside network, has user authen, all transaction
are logged


however this is not cost effective for small networks

REMEMBER: a packet filtering firewall looks at the source address AND the port number of a packet


20. VPN and Tunneling

methods:

L2TP


combines PPP from Microsoft and L2F from Cisco. Uses LNS and LAC

PPTP


enables remote users to log in to a secure server. It will seem like the network is accessed by local
means since it hides the routing and switching process from users
. Provides security for file transfer via
encryption.

IPSec (IP Security)


implemted at Network layer


like SSL and L2TP but does not require IPSec aware
applications. The IPSec SUBprotocols are AH(auth header) and ESP(encapsulating security protocol). I
n order
to authenticate clients and servers IPSec uses and automated key
-
management system called IKE (internet key
exchange)

CHAP (challenge handshake authentication

RAS
-

Remote Access Service for Windws NT/2000

The actual VPN protocols are: GRE, L2F,

PPTP, L2TP (used for IPSec), MPPE (used for Windows dial
-
up
networks ONLY) and IPSec

PPTP ports


you can configure

16,384 ports


21. Digital Carrier Services

DS0 64

DS1 1.544

24 channels

DS3 45

672 channels



8

21a.
OPTICAL Carrier Services

O
C1


51.84 mbps

OC
-
3


155mbps

OC
-
12


622 mbps

OC
-
192

10gbps


22. ICA


Independent Computing Architecture (CITRIX)

Thin client computing. The ICA protocol uses less than 20K. The thin clients connect ot a server and that server

starts the application

executes the app

transfers only the apps interface to the client



Uses a boot ROM to attach to server



Needs a network connection



Emulates complete PC environment



OS is embedded in a ROM


23. Security Protocols

Non
-
repudiation (spoofing) handled by digital s
ignatures

Ciphertext/hash

Make the distinction between ciphers (arrangement of codes) and codes


which are just 1’s and 0’s

Two types of cryptography, Secure key and PKI

Encryption Methods

DES


Digital Encrypt in 64k blocks

Diffie
-
Hellman


PK and sessio
n key

RSA


uses PKI and SSL


SOCKETS

defined as a connection from a client to an endpoint



SSL is the main protocol that uses sockets. Runs at network layer



SSL is NOT and encryption method


it IS a security PROTOCOL



SSL uses BOTH public
-
key and secret
-
ke
y cryptogoraphy



Tunnels are actually big sockets



Has two sub
-
protocols: SSL record protocol and SSL handshake protocol



Kerberos


uses a ticketing system


24. Network Operating Systems

Two types :Client/Server and Peer to Peer

Windows and Linux can operate

as Peer to Peer but Netware cannot


EXAM tip

EXAM tip


all NOS use Administrator, root (or superuser) to signifiy Admin users

Directory services and X.500


the X.500 Dir Services is called the global white pages

NetWare ALERT: netware is a network oper
ating systems ONLY


it has NO client version EXAM tip

Multiprocessor kernel, NLM’s (netware loadable modules), PCI Hotplus

Netware 3.x has a bindery feature


a big database, which ea user needed a login for EACH server!
-

UGH

NetWare PROTOCOLS: IPX (inter
network packet exchange) similair to IP in that it is connectionless
and SPX(sequenced packert exchange) similair to TCP in that it is connectioned oriented

EXAM Netware File Attirbutes: Archive(A), Execute Only(X), Hidden (H), Read
-
Only(RO, R
ead
-
Write(RW) and
Shareable (SH).

UNIX/Linux
-

Multipupose operating system meaning it is considered both a client and a network operating
system

It has protected multitasking, POSIX (portable operating system interface) compliance, shell interface, suppo
rt
for dumb terminals

EXAM tip: versions f UNIX: HP
-
UX, AIX, Solaris, IRIX, Redhat, Slackware, SuSE, Debian GNU

UNIX Basics (EXAM tip)


root user is all powerful. U is user who owns, g is group, r read access, w is write
access and x is execution permissi
on. So basically if you have RWX it grants permission to do everything.

UNIX protocols: UDP, ICMP, NIS, LDAP


25. Network Implementation

Windows NT

Domains and Controllers: Windows uses an organizational concept called domains to spearate
members of a ne
twork, including users, printers and servers. Domain organization is logical, the physical
location DOESN’T matter.

It involves PDC’s and BDC’s (primary and backup domain controllers)


9

The PDC stores the SAM (Security Accounts Manager)

Windows 2000

Active D
irectory becomes available which can handle parent/child domain

AD sets trust relationships


Macintosh

Apple abandon AppleTalk after Mac OS8 in favor of TCP/IP


VLANS 802.1q: A logical LAN within a physical LAN

Benefits and Basics

Fewer switches

Traffic is
olated by groups

Can overlap one another

Three Major Types of VLANS

Port
-
based VLANS (if a repeater is installed in any place it segments by repeater

Mac
-
address
-
based VLANS (routed by MAC address

Protocol
-
based VLANS (Layer 3 Based)


The IEEE 802.1q stand
ard defines VLAN’s using explicit technology rather than implicit. Meaning, that explicit
VLAN’s are either port
-
based or protocol based (NOT Mac
-
based)


Data Storage

Network Attached Storage


be able to note the main characteristics.

TAPE: DAT (Digital A
udio), DLT (Digital Linear), DDS (Digital Data Sortage)

Storage Controller Interfaces:

a. IDE (Integrated Data Environment) slave/master dive relationship,

b. SCSI (higher transfer rates than IDE). Note that SCSI has tweo possible types of terminators

(Passive and Active)

Fiber Channel (faster than SCSI has transfer rates up to 4gbps)

1. Benefits of NAS:

Cross
-
platforms file sharing, Easy backups (using RAID
-

and NAS can support at least RAID 5)

2.

How NAS operates:


a. Operates on client/server premise



access granted via Ethernet


b. NAS devices are usually hard disks using SCSI

26. Data Availability

Fault tolerance concepts

Load balancing: one way is to route each request to a different, identicial server host address in a DNS table

Latency

MTBF (mea
n time between failures

Failover


RAID
:

Redundant Array of Inexpensive Disks

Parity: a bit in the data to determine if it is corrupt

Striping: basically a way of partitioning raid disks into what appears to be the operating systems as on logical
drive. STR
IPED data is written in order and NOT randomly

Disk duplexing: also known as AKA RAID 1 involves storing (“mirrored”) data on not just diff disks BUT also on
diff controllers/channels

RAID 1 = duplexing, RAID 2 = striping with error correction(rearely used
), RAID3


striping with Parity on a
single drive, RAID 4 = block by block on multiple drives and RAID 5 = striping with parity AND supported by
Windows

EXAM tip: When trying to remember how many disk with each RAID just remember that RAID 3 is the FIRST
c
lass that requires 3 disks


all others above it also require at least 3 and the ones below it require two

27. Configuring Remote Connectivity

RAS Connection methods:

PPP

SLIP (mainly used with UNIX) does require a static IP

Microsoft RAS protocol

Encrypti
on: RAS uses CHAP


10

CHAP uses MD5 (message diget) for Hash

Installing and Configuring RAS

Hardware req’d: NIC with NDIS driver, Modem,

If you need more than 254 addresses you’ll need to span across subnets

You can configure up to 16,384 ports

Remember that
L2F encapsulates packets into PPP b/4 transmitting them

Remember that PAP just send stuff in cleartext so is is pretty USELESS

Remember that netsh ras add registeredserver is the COMMAND to addRAS and IAS to Windows Active
Directory.

Firewalls, Proxy Ser
vers and Security

Methods: Packet filters (low security), Application Gateways (aka proxy server firewalls


good security), circuit
level (poorest security) and Stateful Inspection(good security)

A note on Stateful


it keeps a state
-
table of connections
whereby it monitors the state of a TCP connection and
allows traffic accordingly

One of the more popular proxy servers is Wingate and the other (for Linus) is
www.squid
-
cache.com

28. Network Configuration Settin
gs

Nonroutable Protocols


DLC (data Link Control : for printers), NetBEUI

Routable


IPX, TCP/IP

Windows Internet Naming Service (WINS)


used with Microsoft NetBIOS. Enables clients to register NetBIOS
names at startup, and request name resolution

DNS


it is a hierarchical naming system. Resolves hotnames to an IP address

DHCP


automagically assigns IP addresses and cal also provide the addresses of routers, WINS servers, DNS
servers , etc

Uses a form of BOOTP (BOOTPAS protocol)


29. Private IP address
es


these are not routable addresses thru the Internet

10.0.0.0


10.255.255.255

172.16.0.0


172.31.255.255

192.168.0.0


192.168.255.255


3
0
. Linux

NFS


Network Files System

#killall


this command kills the running process on the computer


3
1
. Novell
Netware

Can configure it for both IP and IPX

GSNW


(gateway services for Netware) enables Win NT/2000


3
2
.Troubleshooting by Topology

Ring: one error can bring down the entire ring


Star: the main error issues reside in cabling


Bus: must ensure that cabl
e is properly terminated if a computer/device i
s brought out of the network.


3
3
.
Guidelines for
Assigning IP addresses


1. All devices on subnet must have the same Network ID


2. Node ID’s on local subnet must be unique


3. 127.0.0.1 is
reserved

for loopb
ack


4. Node addresses cannot be all 1’s or 0’s


Subnet

What is masking used for?

It masks what you don’t want to touch (if you have a car, you “mask” the chrome to avoid painting it)

If a user tells you the IP address without the subnet you have nothing

S
ubnet masks
determine

local or remote addresses