Liquid crystal display, light shines through liquid filters
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What are the types of LCD and what do they stand for?
TN \= twisted nemantic IPS \= in plane switching VA \= vertical alignment
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Difference between different LCD types?
TN \= better response time, bad wide angles, low power IPS \= better colors, more expensive, good angles VA \= best contrast, bad angles
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Different types of LCD backlights?
CCFL \= cold cathode fluorescent lamp LED
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What is special about CCFL?
Uses AC power when the computer requires DC, so need an inverter
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How many pins is USB-C? What makes it special?
24pins, can be used to transmit other signals (HDMI, DisplayPort)
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What was used before USB connectivity and with what kind of signal? How many pins?
DB-9 cable with RS232 signal, 9pin
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What kind of stylus' are there?
Capacitive stylus \= touch pen Active stylus \= apple pencil, can communicate independently of the screen
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What is the older type of headset connection? With what type of signal?
3.5mm TRRS (tip ring ring sleeve) with an analog signal
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What were the 2G networks? What did they stand for?
GSM \= global system for mobile communication CDMA \= code division multiple access
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What companies used GSM and how did it work?
AT+T and T-Mobile, has multiplexing
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What does multiplexing mean?
Multiple data signals use the same channel without interference
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What companies used CDMA? How did it work?
Verizon and Sprint, each person used a different code
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What was the purpose of 4G? What did it stand for?
To combine GSM and CDMA, LTE \= long term evolution
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What does EDGE stand for?
Enhanced data rates for GSM evolution
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What is PRL? How does it update?
Preferred roaming list, so your cell phone can connect to the right tower, updates OTA (over the air)
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How does GPS work?
30 satellites in the air, your device needs to see 4 for accurate location
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What does MDM stand for? And do?
Mobile device management, companies can manage user devices through one console
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What is meant by a partition?
Keeping company data and private data separate
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What are the two types of IP payloads? What do they stand for?
TCP \= transmission control protocol UDP \= user datagram protocol
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What does in the clear mean?
Not encrypted
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Why not just have the IP payload?
TCP and UDP allow for multiplexing with different applications and ports
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How does TCP work?
Requires formal setup/teardown process to establish protocol, called a reliable system because will make sure data reaches server, also has flow control to make sure one side is not getting data too quickly
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Examples of TCP?
HTTPS \= hypertext transfer protocol secure SSH \= secure shell
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How does UDP work?
No formal setup process, no confirmation of data sent, for real time communication
Queries \= seeing how the network is functioning over time Traps \= Alerts with problems or changes
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What are the different SNMP versions?
v1 \= 1 query at a time in the clear v2 \= bulk transfers in the clear v3 \= message integrity added, auth, encryption
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LDAP?
Lightweight directory access protocol tcp/389 Store and retrieve info in network directory
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RDP?
Remote desktop protocol tcp/3389 Share desktop for remote location
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What are common devices on a SOHO?
Wireless router, switch, firewall
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What does a router do?
Routes traffic between different IP subnets
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What type of connections can connect to a router?
LAN, WLAN, copper, fiber
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What does a switch do?
Sends info based on MAC address, is the core of an enterprise network
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ASIC?
Application specific integrated circuit, piece of hardware designed for a specific function Ex: digital voice recorder
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What is an unmanaged switch?
Switch with no config options, no management protocols, just plug in and play
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What is a managed switch?
VLAN support, traffic priority options, redundancy support, port mirroring and protocol analyzing, external management (SNMP)
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What is VLAN?
Virtual Local Area Network, can divide different LANs
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STP? (protocol)
Spanning Tree Protocol, prevents loops in a LAN
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How does port mirroring work?
Network monitoring, mirror a port and send packets through the mirror to see what is going on
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How does a patch panel work logistically?
Connect everyone on the floor to a patch panel (permanent connection), have this panel connect with RJ45 connectors than you can change easily
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RJ45 connector?
Ethernet connector
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How does proxying internet traffic work?
Have an intermediary server that scans for malicious data from the internet before coming back to the client
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What are some traits of a proxy server?
Access control, caching, URL filtering
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PoE?
Power over ethernet, data and power in one cable
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Types of power sources for PoE?
Endspan \= power comes from the switch Midspan \= in-line power that is injected between the device and the switch
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PoEaf 2003?
15.4W DC, 350mA max current
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PoE+at 2009?
225W DC, 600mA
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PoEbt 2018?
Type 3 \= 51W 600mA Type 4 \= 71.3W 960mA
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What is a hub? Communication?
Before switches, data goes into one port and is sent to all other ports, half-duplex
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What does duplex mean?
Data can be sent in both directions at the same time
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What is a cable modem?
Copper cable connection for TV and internet, broadband connection, allows for the transmission of different data types across multiple frequencies
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DOCSIS?
Data over cable service interface specification
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DSL? How does it work and distance?
Digital subscriber line, telephone wire for internet, speed gets worse the farther away you get from the central office
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ADSL?
Asymmetric digital subscriber line, because the download speed is greater than the upload speed
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ONT?
Optical network terminal, fiber cable connects to box outside location to convert it to copper
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What is a demarcation point? Another name for it?
Also called demarc, when the public network becomes your network
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NIC?
Network interface card
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SDN?
Software defined networking, taking switches, routers, etc. and making them software
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What are three layers of devices?
Infrastructure layer \= data plane of that device (forwarding, encrypting) Control layer \= the brain (routing table, session table) Application layer/management \= manage device using an API
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What does NAT mean?
Network address translation
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What does API mean?
Application programming interface
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What does the difference in frequency mean for a wireless network in terms of range?
Higher frequency \= more objects in the way will absorb therefore less range Lower frequency \= objects will bounce the signal therefore more range
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What is the problem with 2.4GHz frequency?
Lots of other devices use this frequency (baby monitor, phones, bluetooth)
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802.11a?
1999, 5Ghz freq, 54Mbits/s
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802.11b?
2.4GHz, 11Mbits/s
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802.11g?
2003, 2.4GHz, 54Mbits/s, backwards compatible with A and B
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802.11n?
2009, WiFi4, 5GHz or 2.4GHz, 40MHz channel widths with 4 antennas, 600Mbits/s, MIMO