Networking Flashcards
What does TCP/IP stand for?
Transmission Control Protocol/Internet Protocol
What is TCP?
Transmission Control Protocol
Connection-oriented
– A formal connection setup and close
- “Reliable” delivery
– Recovery from errors
– Can manage out-of-order messages or retransmissions - Flow control
– The receiver can manage how much data is sent
What is UDP?
User Datagram Protocol
* Connectionless - No formal open/close to the connection
- “Unreliable” delivery
– No error recovery
– No reordering of data or retransmissions - No flow control
– Sender determines the amount of data transmitted
When would you use UDP?
Real-time communication
– There’s no way to stop and resend the data
– Time doesn’t stop for your network
Connectionless protocols
– DHCP (Dynamic Host Configuration Protocol)
– TFTP (Trivial File Transfer Protocol)
What does DHCP stand for?
Dynamic Host Configuration Protocol
What does TFTP stand for?
TFTP (Trivial File Transfer Protocol)
When would you use TCP? (and with what?)
- Connection-oriented protocols prefer a “return receipt”
– HTTPS (Hypertext Transfer Protocol Secure)
– SSH (Secure Shell) - The application doesn’t worry about out of order
frames or missing data
– TCP handles all of the communication overhead
– The application has one job
What are Non-ephemeral ports ?
permanent port numbers
– Ports 0 through 1,023
– Usually on a server or service
What are ephemeral ports ?
- Ephemeral ports – temporary port numbers
– Ports 1,024 through 65,535
– Determined in real-time by the client
Port numbers range
TCP and UDP ports can be any number between
0 and 65,535
* Most servers (services) use non-ephemeral
(not-temporary) port numbers
– This isn’t always the case
– It’s just a number.
T or F – TCP port numbers aren’t the same as UDP port number
T
T or F - TCP and UDP are encapsulated within IP.
T
What is SSH?
SSH - Secure Shell
* Encrypted communication link in terminal communication between systems
What are Routers?
Routes traffic between IP subnets
– Makes forwarding decisions based on IP address
– Routers inside of switches sometimes called
“layer 3 switches”
* Often connects diverse network types
– LAN, WAN, copper, fiber
What are Switches?
- Bridging done in hardware
– Application-specific integrated circuit (ASIC)
– Forwards traffic based on data link address - Many ports and features
– The core of an enterprise network
– May provide Power over Ethernet (PoE) - Multilayer switch
– Includes routing functionality
What are Unmanaged Switches?
- Very few configuration options
– Plug and play - Fixed configuration
– No VLANs - Very little integration with other devices
– No management protocols - Low price point
– Simple is less expensive
What are managed Switches?
- VLAN support
– Interconnect with other switches via 802.1Q - Traffic prioritization
– Voice traffic gets a higher priority - Redundancy support
– Spanning Tree Protocol (STP) - Port mirroring
– Capture packets - External management
– Simple Network Management Protocol (SNMP)
What are Access points?
Not a wireless router
– A wireless router is a router and an access point
in a single device
* An access point is a bridge
– Extends the wired network onto the wireless network
– Makes forwarding decisions based on MAC address
What are Patch Panels?
Combination of punch-down blocks and
RJ-45 connectors
* Runs from desks are made once
– Permanently punched down to patch panel
* Patch panel to switch can be easily changed
– No special tools
– Use existing cables
What are Firewalls?
- Filters traffic by port number
– OSI layer 4 (TCP/UDP)
– Some firewalls can filter based on the application - Can encrypt traffic into/out of the network
– Protect your traffic between sites - Can proxy traffic
– A common security technique - Most firewalls can be layer 3 devices (routers)
– Usually sits on the ingress/egress of the network
What is Power over Ethernet (PoE)?
Power provided on an Ethernet cable
– One wire for both network and electricity
– Phones, cameras, wireless access points
– Useful in difficult-to-power areas
* Power provided at the switch
– Built-in power - Endspans
– In-line power injector - Midspans
What is PoE switch?
- Power over Ethernet
– Commonly marked on the switch or interfaces
Explain PoE, PoE+, PoE++
- PoE: IEEE 802.3af-2003
– The original PoE specification
– Now part of the 802.3 standard
– 15.4 watts DC power, 350 mA max current - PoE+: IEEE 802.3at-2009
– Now also part of the 802.3 standard
– 25.5 watts DC power, 600 mA max current - PoE++: IEEE 802.3bt-2018
– 51 W (Type 3), 600 mA max current
– 71.3 W (Type 4), 960 mA max current
– PoE with 10GBASE-T
Explain Hub
- “Multi-port repeater”
– Traffic going in one port is repeated to
every other port - Everything is half-duplex
- Becomes less efficient as network traffic increases
- 10 megabit / 100 megabit
- Difficult to find today
Explain Cable modem
- Broadband
– Transmission across multiple frequencies
– Different traffic types - Data on the “cable” network
– DOCSIS (Data Over Cable Service Interface Specification) - High-speed networking
– Speeds up to 1 Gigabit/s are available - Multiple services
– Data, voice, video
Explain DSL modem
- ADSL (Asymmetric Digital Subscriber Line)
– Uses telephone lines - Download speed is faster than the upload
speed (asymmetric)
– ~10,000 foot limitation from the central office (CO)
– 52 Mbit/s downstream / 16 Mbit/s upstream are
common
– Faster speeds may be possible if closer to the CO
Explain ONT
Optical network terminal
– Fiber to the premises
* Connect the ISP fiber network to the copper network
– Demarcation point (demarc) in the data center
– Terminal box on the side of the building
* Line of responsibility
– One side of the box is the ISP
– Other side of the box is your network
Explain NIC
Network Interface Card (NIC)
* The fundamental network device
– Every device on the network has a NIC
– Computers, servers, printers, routers, switches,
phones, tablets, cameras, etc.
* Specific to the network type
– Ethernet, WAN, wireless, etc.
* Often built-in to the motherboard
– Or added as an expansion card
* Many options - Single port, multi-port, copper, fiber
Explain SDN
SDN (Software Defined Networking)
* Networking devices have different functional
planes of operation
– Data, control, and management planes
* Split the functions into separate logical units
– Extend the functionality and management
of a single device
– Perfectly built for the cloud
* Infrastructure layer / Data plane
– Process the network frames and packets
– Forwarding, trunking, encrypting, NAT
* Control layer / Control plane
– Manages the actions of the data plane
– Routing tables, session tables, NAT tables
– Dynamic routing protocol updates
Application layer / Management plane
– Configure and manage the device
– SSH, browser, API
Explain Wireless standards 802.11a
- One of the original 802.11 wireless standards
– October 1999 - Operates in the 5 GHz range
– Or other frequencies with special licensing - 54 megabits per second (Mbit/s)
- Smaller range than 802.11b
– Higher frequency is absorbed by objects in the way - Not commonly seen today
Explain Wireless standards 802.11b
- Also an original 802.11 standard - October 1999
- Operates in the 2.4 GHz range
- 11 megabits per second (Mbit/s)
- Better range than 802.11a, less absorption problems
- More frequency conflict
– Baby monitors, cordless phones,
microwave ovens, Bluetooth - Not commonly seen today
Explain Wireless standards 802.11g
- An “upgrade” to 802.11b - June 2003
- Operates in the 2.4 GHz range
- 54 megabits per second (Mbit/s) - Similar to 802.11a
- Backwards-compatible with 802.11b
- Same 2.4 GHz frequency conflict problems as 802.11b
Explain Wireless standards 802.11n
802.11n (Wi-Fi 4)
* The update to 802.11g, 802.11b, and 802.11a
– October 2009
* Operates at 5 GHz and/or 2.4 GHz
– 40 MHz channel widths
* 600 megabits per second (Mbit/s)
– 40 MHz mode and 4 antennas
* 802.11n uses MIMO
– Multiple-input multiple-output
– Multiple transmit and receive antennas
Explain Wireless standards 802.11ac
802.11ac (Wi-Fi 5)
* Approved in January 2014
– Significant improvements over 802.11n
* Operates in the 5 GHz band
– Less crowded, more frequencies (up to 160 MHz
channel bandwidth)
* Increased channel bonding - Larger bandwidth usage
* Denser signaling modulation
– Faster data transfers
* Eight MU-MIMO downlink streams
– Twice as many streams as 802.11n
– Nearly 7 gigabits per second
Explain Wireless standards 802.11ax
802.11ax (Wi-Fi 6)
* Approved in February 2021
– The successor to 802.11ac/Wi-Fi 5
* Operates at 5 GHz and/or 2.4 GHz
– 20, 40, 80, and 160 MHz channel widths
* 1,201 megabits per second per channel
– A relatively small increase in throughput
– Eight bi-directional MU-MIMO streams
* Orthogonal frequency-division multiple access (OFDMA)
– Works similar to cellular communication
– Improves high-density installations
Explain RFID
RFID (Radio-frequency identification)
* It’s everywhere
– Access badges
– Inventory/Assembly line tracking
– Pet/Animal identification
– Anything that needs to be tracked
* Radar technology
– Radio energy transmitted to the tag
– RF powers the tag, ID is transmitted back
– Bidirectional communication
– Some tag formats can be active/powered
Explain NFC
NFC (Near field communication)
* Two-way wireless communication
– Builds on RFID, which is mostly one-way
* Payment systems
– Major credit cards, online wallets
* Bootstrap for other wireless
– NFC helps with Bluetooth pairing
* Access token, identity “card”
– Short range with encryption support
802.11 technologies (big picture)
- Frequency
– 2.4 GHz or 5 GHz
– And sometimes both - Channels
– Groups of frequencies, numbered by the IEEE
– Non-overlapping channels would be ideal - Regulations
– Most countries have regulations to
manage frequency use
– Spectrum use, power output,
interference requirements, etc.
bluetooth technologies (big picture)
- Remove the wires
– Headsets, speakers, keyboards / mice - Uses the 2.4 GHz range
– Unlicensed ISM
(Industrial, Scientific and Medical) band
– Same as 802.11 - Short-range
– Most consumer devices operate
to about 10 meters
– Industrial Bluetooth devices can communicate
over 100 meters
what is DNS server
Domain Name System
– Convert names to IP addresses
– And vice versa
* Distributed naming system
– The load is balanced across many different servers
* Usually managed by the ISP or IT department
– A critical resource
what is DHCP server
DHCP server
* Dynamic Host Configuration Protocol
– Automatic IP address configuration
* Very common service
– Available on most home routers
* Enterprise DHCP will be redundant
– Usually running on central servers
what is File server
File server
* Centralized storage of documents,spreadsheets,
videos, pictures, and any other files
– A fileshare
* Standard system of file management
– SMB (Server Message Block),
Apple Filing Protocol (AFP), etc.
* The front-end hides the protocol
– Copy, delete, rename, etc.
