Part I Flashcards
Define Network
a collection of devices which are connected together allowing them to communicate with one another.
Node/Host
each device ona network
Client
a standard computer you may find on an office desk or at home.
Server
a big and powerful computer which can be accessed by many client computers at the same time.
Peer to Peer Network (Workgroup)
taking a few systems and connecting them together.
Client/Server Model (Domain)
one system (server) is responsible for all the user accts and groups for the entire network.
UNC (Universal Naming Convention) Path or local path
\Server\Share\Folder\File
\DC01\Files\Temp\doc.txt
LAN (local area network)
a small network contained to a single bldg or floor of a large bldg.
WAN (wide area network)
spans large distances
Host
any device that is connected to a network
TCP/IP (Transmission Control Protocol/Internet Protocol)
term used to identify all of the different protocols used on networks using IP addressing
Ethernet Fast Ethernet Gigabit Ethernet 10 Gb Ethernet T1
10Mbps 100Mbps 1Gbps 10Gbps 1.544Mbps
User Permissions
used to control the level of access that a user has to specific resources like files, folders and printers
User Rights
used to restrict a users ability to perform specific actions like installing a new program, changing system time, creating user accts, or changing screen savers.
Domain Controller
a server that centrally manages user accounts for the domain.
ADUC (active directory users and computers)
allows network admins and technicians access to perform various administrative tasks remotely accross the network.
Local Profile
a prifile local to one computer
Roaming Profile
your profile remains consistent regardless of the computer you log into on the domain.
Default Users Profile
used as a template for all users that log onto a computer for the first time.
Registry
a centralized database that holds all informatin relating to user’s profiles, hardware and software installed on the computer.
NTUSER.dat
file that stores user profile information
Home Folder
a shared folder on a server where a user can store their data.
Mailbox-enabled objects
allowed to send and receive mail
Mail-enabled objects
has an e-mail address, but no mailbox
Service
a program that runs in the background performing some type of task. Does not require user interaction.
3 Common network topologies
- Bus
- Ring
- Star
Hub
- common connection point for devices in a nework.
- Contains muliple interfaces
- a layer one device
- Uses half duplex
Frame
- the basic unit of data transmission on a network.
- usually transmitted serial bit by bit.
- the entire string of bits
Protocol
a set of rules that define the proper operation of a task.
Address
unique bits assigned to each individual computer on a LAN
Header
first bits of a frame which include addresses of the sending and receiving computers
Error detection
a way to figure out if what a computer received is exactly what was sent.
Checksum
a way to check and see if what was sent was actually received.
FCS (frame check sequence)
- a way to calculate the header and data to equal to the trailer
- sometimes called the trailer
- extra bits added to the frame for error detection
CRC (cyclic redundancy check)
- a code used for detecting accidentall changes in a string of bits
- similar to the FCS
Trailer
generic term used for the FCS/CRC of a frame to indicate it shows up at the end of a bit string.
Error Detection
process of figuring out that there was an error somewhere in a string
Network Packet
used to describe the bit string sent by computers on a network
3 types of frames
- Unicast
- Broadcast
- Multicast
Unicast
a frame destined from one single computer to another single computer
Broadcast
a frame destined from one computer to all the other computers on the network
Multicast
a frame destined from a computer to many but not all other computers.
OSI Model
a 7 layer model that is the most common way to illustrate the different things that happen when you connect to a network.
OU (organizational unit)
- allows NW administrators to sub-divide a domain into smaller, more manageable chunks.
- contains users, groups, computers.
- are often created to organize them by dept, job function or location
Object
any item found in the OU’s such as, groups and computers
Layer 1 - Physical Layer
- describes how the bits will get onto the network
- cables and things you plug into
Layer 2 - Data Link Layer
- Creates the frames that are needed to get data across one NW
- Defines specific number of bits that ID each host on a given NW
- Ethernet and wireless are used with this layer
Layer 3 - Network Layer
- Allows you to interconnect to many different NW’s of all different physical types
- Primary responsibilities are logical addressing and routing
- IP is used with this layer
- Adds bits between layer 2 and data (IP addresses)
Layer 4 - Transport Layer
- Where TCP/IP belongs
- Responsible session establishment, flow control and error correction
- Ensures the data sent from one host to another across the NW arrives correctly
Layer 5 - Session layer
-Supposed to be the layer that manages the connections between applications on different systems.
Layer 6 - Presentation Layer
-Theoretically converts the data from the format that the other layers like into the format that the application likes
Layer 7 - Application Layer
- Layer closest to the end user
- HTTP, SMTP and RPC
- Allows different applications to talk to each other over the NW
MAC (Media Access Control)
- a NW card’s layer 2 address
- 6 bytes long: 00-90-21-DE-1A-71
Ethernet
- is a layer 2 protocol
- 6 byte HEX addresses
- You can combine copper and fiber ethernet
- Operates at both layer 1 and layer 2 of the OSI Model
NIC (Network Interface Card)
a computer circuit board or card that is installed in a computer so that it can be connected to a NW
Driver
- A set of software that tells your OS how to use your hardware.
- Has to be compatible to OS used
Collision
when 2 hosts try to send at the same time, on the same shared cabling system, the bits will overlap causing errors.
CSMA/CD (carrier sense milti access w/collision detection)
- Handles collisions when a NW is using half duplex
- Listens first
Duplex
each host on the NW can send and each host can receive
Half-duplex
only on host can be communicating at any time
2 most common types of cabling
- UTP (unsheilded twisted pair)
- STP (sheilded twisted pair)
2 types of Ethernet cabling
- Straight through cable
- Crossover cable
Full Duplex
devices can send and receive at the same time
Switch
- Used to interconnect nodes on an Ethernet LAN
- Have the ability to hold or buffer packets coming over the NW
- Can keep track of MAC addresses
- Operates at layer 2 runs on Full Duplex
Bandwidth
the max amount of data Ethernet can trasfer
IP Address
- most common NW protocol
- is the standard for the internet
- allows you to cnnect from one NW to another
ARP (Address Resolution Protocol)
takes the IP address of the system we want to talk to and uses that to find the system MAC address so we can unicast to it.
Router
- a dedicated NW device that provides a number of services on a NW
- Allows you to connect to differnt types of NW’s
- Operates at layer 3
- blocks all broadcasts to save bandwidth
Default Gateway Address
the IP address of the router that will be used, by default, to reach other NW’s
Collision Domain
the group of devices that can collide with one another
Forwarding
choosing to retransmit the fram on one specific interface
Filtering
choosing not to send the fram out any other interface
Flooding
if a switch has no MAC address enter in it’s table, it will send out the fram to all interfaces except the one it was received on.
Media Layers (bottom 3 layers)
usually responsible for delivery of data from host A to host B through hubs, switches, and routers.
Host Layers (top 4 layers)
- ensures applications run correctly between 2 hosts.
- are responsible for translating the data bits using the ASCII table
- HTTP, SMTP, RPC, TCP, UDP
Encapsulation
process of adding headers and trailers at the originating host to prepare data so it can be sent over a NW
De-encapsulation
process of stripping headers and trailers at the ultimate destination host to see waht data is being received
Subnet mask
numbers used to tell you which part of an IP is the NW portion and which is the host portion
Loopback address
used for testing purposes 127.0.0.0
NAT (Network Address Translation)
- translates private IP’s into public addresses.
- used by routers
APIPA (Automatic Private IP Addressing)
IP address used if you can’t conect to the DHCP server. 169.254.x.x
ICMP (Internet Control Message Protocol)
ECHO messages to test communications
Ping
toos used for testing TCP/IP communications between 2 machines.
tracert
command used to show you the path of the packet as it travels to the destination machine.
Default Gateway
IP host address of the router that gets the packet of their NW when the destination is on another NW
Subnetting
provides a way to divide up IP networks into smaller pieces.
Subnet
refers to one of these smaller NWs
CIDR (Classless Inter-Domain Routing)
allows you to change the subnet mask w/o any regard to the class of address you are using
UDP (User Datagram Protocol)
- transport protocol
- a connectionless protocol
- a host can send a data across the NW w/o checking first
- better for speed
TCP (Transport Control Protocol)
- connection-oriented protocol
- TCP must establish a connection or session w/another host before it starts sending data
- better reliability
- provides error recovery & guarantees delivery of the packet
Significant Port Numbers
SMTP - 25 DNS - 53 HTTP - 80
Telnet - 23 TFTP - 69 DHCP - 67s, 68c
HTTPS - 443
TCP Handshake (definition)
the process of establishing a session between a client and server (client usually starts it)
TCP Handshake (process)
- the client is asking to synhronize setting for this session (SYN)
- the request must be acknowledged by the server (ACK)
- second synch is sent by the server requestin specific data (SYN)
- Client send an acknowledgement back to the server (ACK)
DHCP (Dynamic Host Configuration Protocol)
a protocol used to configure TCP/IP settings automatically to devices.
DORA
1) Client broadcasts a DISCOVER message containing its MAC
2) Server hears the message, reserves an address from its pool and replies with an OFFER broadcast saying there is an address available
3) Client hears offer and accepts in the form of a REQUEST broadcast
4) Sever hears the request and replies with an ACKNOWLEDGE broadcast to seal the deal
Lease
the process of a DHCP server giving a PC TCP/IP information for a limited period of time (8 days)
Name Resolution
the process ofmapping a PC name to an IP address
DNS (Domain Name System)
it translates easily memorized domain names to the numerical IP addresses
File Server
a server that stores large amounts of user data in a secure and centralized manner
Home Folder
used to store large amounts of individual user data in a centralized location.
Profile Folder
stores user environment setting like, wallpaper, folder options, desktop and My Documents contents
Personal Folder
actually files that contain emails, contacts, tasks, appts, and other options you configure in MS Outlook
Distribution Groups
- Used when you need to send email to a group of users.
- provides an easy way to grop together users that require the same email distributions
- Can’t be assigned permissions
Security Groups
- used when you need to grop users together and assign them permissions
- Only they can be placed on a NW resources ACLs
- Most commonly used group
Domain Local Group
- assigned to local domain resources for the purpose of assigning specific permissions
- Cannot exist in another domain
Global Groups
- used to group users by function, department or role
- Can only contain members that exist in its own domain (users & PCs)
- Place user accts here
- Can become members of Domain Local Groups in any domain
Universal Groups
- used to allow access to resources that exist in any domain in the environment.
- Can contain members that reside in any domaine
Group Nesting
when you add one group as a member of another grouup.
AGDLP
- Accts: create domain user & PC accts
- Global Groups: user & PC accts are added to GG
- Domain Local Grouop: GG that now contains user & PC accts are added to domain local group
- Permissions: once GGs have been nested into Domain Local Groups, the DLGs are added to the ACL of NW resources & permissions are assigned
AGDLP
- Create user & PC accts
- Add user & PC to GG
- Nest GG into DLG
- Add DLG to resources ACL
- Assign permissions to the DLG
Print Server
a PC installed w/printer software and maintains connectivity to multiple printers for dentralized admins
Printer
a device driver, which is software that tells the Os how to access the print device
Print device
the actual physical device that feeds out a paper copy of a document
Printer Pooling
- method of load balancing
- one printer with connected to multiple devices
RAID (Redundant Array of Independent Disks)
- allows our data to be written to & read from the HD faster
- allows you to add more storage space for users
- allows you to recover from HD failures
RAID 0
combines unallocated space from 2 or more dynamic disks to create a volume that acts like one drive
- Uses striping to give the disk performance faster R & W access to disks
- Data is saved equally among all disks
RAID 1 or Disk mirroring
- Data is saved to the main disk and copied over to the other disk creating a duplicate or mirror of the main disk
- Write performance is not as good as Striped volume
- Uses split seek
3 characteristics of RAID 1
- Disk fault tolerance
- Increased disk read performance
- Must be a toal of 2 HDs available
Split Seek
process that will allow the Os to access whatever HD that does not have any read queues or has the fewest queues
RAID 5
- Disk stripping with Parity
- Has fault tolerance
- Increased R & W performance
- Must be a minimum of 3 HDs
- Data is saved equally among all disks
Scope
a valid range of IP’s which are available for assignment or lease to client PCs
Renew
- When the PC contacts the DHCP server requesting to keep TCP/IP info
- More specific and take a higher priority
Scope options
allow you to assign TCP/IP info to individual NWs that require TCP/IP info specific to that NW
DHCP requirements
- DHCP Scopes must be activated
- DHCP Server must be authorized in AD
- DHCP Service must be started
Reservations Node
if you want a PC to receive a specific IP address that is part of your range of IPs you configured for your scope
Server Options
-Used when you want all your DHCP clients to have the same settings
DHCP Relay Agent
listens for DHCP broadcasts on its subnet and communicaties with the DHCP server on another NW on behalf of the client
IP Helper Address
-Responsible for listening to DHCP broadcasts and allows DHCP broadcasts, but blocks all other broadcasts
