Network Terminology and Basics Flashcards
Network Switch Function
Is the center of a network.
It allows all of the host devices on a network to communicate with each other.
Network Host
Is a device that can be communicated with and actively participates on a network - you can contact it and get a response.
Define Ethernet and WiFi
Ethernet is the technology to used to physically wire LANs; it is the wired network.
The wireless network is called WiFi.
Router Function
Connects two or more hosts together
Allows hosts to communicate with hosts beyond the LAN.
AP Function
Enables non-wired devices to connect to a network
Converts the wired signal to a wireless radio signal
MPU Function
Gives options for how power is distributed to your network.
It can also be controlled through the network.
Modem function
Is a “modulator/demodulator”
It translates the carrier signal into Ethernet format used by LANs
Disadvantages of All-in-one Modems
Are optimized for cost, not performance
Generally fine for small networks
Poor wireless performance
Few network switch ports
Seldom built from high-end components
All together, poorer network capacity, speed, and performance
Define “Protocol”
The rules and conventions that computers on a network follow/use to communicate
protocols specify how data is formatted when it is sent and what to do with it once received
TCP/IP meaning
Transmission Control Protocol / Internet Protocol
= internet protocol suite
TCP/IP suite purpose
It is the principle set of rules for exchanging data between computers; it is the language of the internet
Used within a single network or across a series of interconnected networks
Is designed to not route private IP addresses over the internet, it is “unroutable”
When the big-routers (ISPs, gov’t, etc.) receive a packet with a source or destination that is a private address, they drop it
What are the Network Host Configuration parameters?
1) IP Address
2) Subnet Mask
3) DNS Server
4) Default Gateway
Describe “IP Address”
Is 4 decimal numbers of 8-bits each, therefore it’s referred to as a 32-bit address. We use decimal numbers to make is easier for our minds to process.
Describe “Subnet Mask”
it determines/limits how many hosts can be on a network, determines the size of the TCP/IP network
A host uses its Subnet Mask parameter to split its IP address in two.
- On one side is the shared network address
- The other side is the unique address for that individual host
Describe “DNS Server”
“Domain Name System”
The phone book of the internet, it is a distributed network of Internet servers that work together to translate human-friendly domain names into computer-friendly IP addresses
Describe “Default Gateway”
What is it and what is it’s role?
Is the router.
When a host’s subnet mask reveals that the receiving host is on a different network, it will then communicate with the default gateway/router, which will then forward the message via the WAN to the recipient.
Define the term “Subnet”
Is a smaller network that is part of a larger network. Will also hear “broadcast domain” when talking about network traffic within a subnet.
A host uses its Subnet Mask parameter to determine whether another host is either on, or, somewhere beyond its local subnet.
Two hosts on the same subnet can communicate directly with each other; otherwise, they will need help to communicate between the two networks (e.g., a Router)
DHCP Meaning
Dynamic Host Configuration Protocol
Is the protocol used to configure hosts dynamically on a network.
What is the default DHCP range for Araknis routers?
192.168.1.100 to 192.168.1.199
Self-assigned IP Addresses
Begin with 169.254.x.x, aka “link-local;” the switch won’t forward information beyond the switch
Means there is something wrong with the the DHCP service
What is an octet?
8-digits in binary that correspond to a decimal number
What is a bit?
Binary digit
How are decimal numbers converted to binary and binary converted to decimal?
Decimal values increase by a factor of 2: 128, 64, 32, 16, 8, 4, 2, 1
Add/subtract the the binary’s values’ decimal equivalent based on the placeholder location.
What is the highest decimal number that can be in an IP address octet?
255 because the decimal equivalent of 11111111 =255
128+64+32+16+8+4+2+1 = 255
If two devices trying to communicate are not on the same subnet mask, what is needed to enable communication?
A router
What divides an IP address into two parts, and what are these two parts?
The subnet mask
It divides the IP address into the network address and the host address, where in binary, the network is represented by 1s, and the host is represented by 0s
What determines the number of IP addresses available on a network?
The subnet mask
How many possible numbers are available in a binary octet of x.x.x.11111111
What built-in addresses reduce this number?
255, but the first and last IP addresses in a range are reserved:
- the network address will be x.x.x.0
- the broadcast address will be x.x.x.255
(or other first and final numbers in a subnet mask… think CIDR)
What are the three rules for IP addresses?
1) Every host on a network must have a unique IP address
2) The lowest address on a network (where all host bits are 0) is the address of the network itself.
3) The highest address on a network (where all host bits are 1s) is reserved for broadcast
If more than 254 IP Addresses are needed on a network, what must be adjusted?
The subnet mask.
Adjust only for the needs - plus some growth - to select the best subnet mask to meet the number of hosts required.
By adjusting from 255.255.255.0 to 255.255.254:
- the usable IPs now span 192.168.0.0 through 192.1.255)
-therefore, the number of usable IP addresses doubles from 254 to 510 possible IP addresses)
- In binary went from 11111111.11111111.11111111.00000000 to 11111111.11111111.11111110.00000000
CIDR role
Aka “slash notation”
Is a quick way to identify the number of network bits in a subnet mask:
255.255.255.0 = 11111111.11111111.11111111.00000000 = /24
Spelled out:
“Classless Inter-domain Routing”
When adjusting the subnet mask for most homes and small business networks, which octet is most commonly changed?
The third octect
Public v. Private IP addresses
Public: are managed and assigned by a governing body for organizations such as ISPs, who then assign those public IP addresses to servers and other host devices.
- Each host connected directly to the Internet must have a public address that is unique and not used by any other host on the Internet.
Private: a unique identifier for hosts connected to a private network, e.g., home network.
What are the three private IP address ranges?
10.0.0.0 (= SM 10.255.255.255 = /8)
- Typically businesses
172.16.0.0 (= SM 172.31.255.255 = /16)
192.168.0.0 (= SM 192.168.255.255 = /16)
- Typically homes
True or false: it is good practice to configure your router to use a third-party DNS server
True
Example: Google’s 8.8.8.8 and 8.8.4.4
What is the purpose of running a Ping?
Serves to identify how the computer uses its DNS Server setting to resolve a user-friendly domain name to a computer-ready IP address
Translate DNS
Domain Name System
What is the Network ID?
The first IP address in each sub-network
What is the first host IP in a network?
The Network ID +1
The first IP address after the network ID
What is the Broadcast IP?
The last IP address in a subnet
What is the last host IP?
The Broadcast IP -1
It’s the final host address before the broadcast address
In subnetting, when does the next subnet/network begin?
With the network ID of the next subnet, which is immediately after the previous subnet’s Broadcast IP
Previous subnet’s Broadcast IP +1 = next network address
How do you determine the number of possible IP addresses on a network?
Can use CIDR/slash-notation
/25 = 128 IPs
/26 = 64 IPs
/27 = 32 IPs
What does “OSI” stand for?
Open Systems Interconnection Reference Model
What are the layers of the 5-layer OSI Model?
5) Application
4) Transport
3) Network
2) Data link
1) Physical
Describe OSI Layer 5
Application layer
Is the end-user layer, the program that opens what is to be sent/received
Serves as the window for users and application processes to access the network services
Describe OSI Layer 4
Transport layer
TCP and UDP: host-to-host, flow control
Ensures that messages are delivered error-free, in sequence, and with no losses or duplications
Describe OSI Layer 3
Network layer
Routers
Where packets of IP Addresses are made/used
Controls the operations of the subnet, deciding which physical path the data takes
Describe OSI Layer 2
Data Link layer
Switches
Makes/reads frames: must have a header of a MAC Address and checksum
- ARP happens here (uses MAC addresses to communicate on same network)
Provides error-free transfer of data frames from one node to another over the physical layer
Describe OSI Layer 1
Physical layer
The physical structure: cables, hubs, etc.
Is concerned with the transmission and reception of the unstructured raw bit stream over the physical medium
What is a packet sniffer?
A protocol/network analyzer.
It is a piece of hardware or software used to monitor network traffic.
Example: Wireshark
What is a destination port?
It is a data identifier that gets attached to a communication coming from the Application layer so that the host receiving it on the other end knows which application the data is meant for.
SMTP: Port 25
HTTP: Port 80
DNS: Port 53
What is a switching loop?
When all switches in a network are connected to one another
Think of a connection triangle in a network when there are three switches.
No clear core and edge switches
What is the maximum Wattage a standard POE device requires?
15.4 Watts
What is the maximum Wattage a POE+ device requires?
Up to 30 Watts
What does a POE injector do?
Can power a POE device from a non-POE switch
Define SFP
Small Form-factor Pluggable
Is a port on a switch most commonly used with fiber-optic
Single-mode fiber optic cables
- have a small glass core (think laser light)
- transmit over 100km without attenuation
- is very expensive
Mode: the pathway that light takes through the glass core to transmit data
Multi-mode fiber-optic cables
- large glass core (think flashlight)
- transfers up to 2km
- cheaper than single-mode
Mode: the pathway that light takes through the glass core to transmit data
Unicast traffic
Communication goes to one device, whether on the network or via the router
Broadcast traffic
Communicates only within its broadcast domain
Broadcast domain
Multicast traffic
Supports the need from one to many domains
Is similar to broadcast traffic, but can be controlled with a group of IP addresses:
- IP Multicast Group Addresses: 224.0.0.0 - 239.255.255.255
- this makes it easier for hosts to read, join, or drop a multicast transmission
- is also easier for the network administrator to pinpoint multicast traffic on a network
What is the IP range used for multicast traffic?
224.0.0.0 - 239.255.255.255
Define VLAN
Virtual LAN
- ports on a single switch can be assigned to different IP sub-networks of a larger network
- help isolate network traffic as if it were running on different networks with completely different switches.
- Can help to provide increased security
*Seldom used in small-to-medium networks, may cause more problems than the’re worth
Define STP
Spanning Tree Protocol
A protocol that monitors the network looking for switching loops
When a switching loop is detected, STP breaks the loop by creating a path to specific ports and blocking others.
What is a Root Bridge?
With STP, it is the switch that decides which path the traffic should take from one switch to another.
Best practice: the root bridge is the switch closest to the router.
Picture upside down tree, the upper portion is the root bridge and it’s the root of the tree through which all traffic must flow
Link Aggregation Control Protocol (LACP)
Allows you to combine multiple links into a single, higher-bandwitdth link
For example, using two uplinks running parallel (on the same two devices): each uplink can maintain 1Gps, but allows for combined data streams of up to 2Gps.
It also created redundancy: if one uplink fails, the other still works.
Media-Over-Coax (MoCA) Network disadvantage
May accidentally result in a switching loop because some media devices (e.g., Sonos) produce their own network.
Why are firmware updates important?
They help to fix problems, improve user interfaces, and add features.
Bridge Mode
Turns off an ISPs combo unit’s router functionality so that all it does is translate the ISP’s WAN signal to a LAN signal
What is DMZ?
Used when the ISP doesn’t allow for the modem to be put into Bridge Mode
While keeping the ISP routing functionality in place (unlike Bridge Mode), it effectively allows all network traffic to be forwarded through the modem to the WAN IP of the internal router.
What is Network Address Translation (NAT)?
Translates network traffic between public and private IP addresses.
Double-natting (modem not put into bridge mode but also have a router) results in a routing hop and more latency.
Why do some routers have more than one WAN port?
The second WAN port is a reliability feature.
By having a second WAN port, you can connect a second ISP for redundancy (aka failover) when the main ISP has an outage.
How does a router “declare” the network?
The router doesn’t know which is the WAN and LAN port, it simply connects two networks together.
However, its two roles make it so that the router creates the internal network, it “declares” it:
1) it’s role as the default gateway for the network
2) it’s role as the DHCP server for the network
On the WAN side it joins the network, on the LAN side, it “declares” the network.
What are the four steps in the Plan the LAN workflow?
1) Size the network
2) Select the networks address
3) Assign addresses for the hosts
4) Implement the network and configure hosts to match your plan
What is a VLAN?
Virtual Local Area Network
Is another LAN, logically separated on its own subnet or broadcast domain by using the same physical network
It lies somewhere between OSI Layers 2 and 3
What is VLAN Tagging?
Think of it like a luggage tag.
As packets flow through the managed switch or router, a special identifier (VLAN ID, or VID) is added to the frame header, right after the source MAC address, making it “tagged.” All frames are either tagged or untagged.
If you setup additional VLANs, leave the traffic for the original/default LAN as untagged.
Network traffic for the default LAN (Untagged) and VLAN2 (tagged) can both pass through the same port on the router to the managed switch.
Modern routers and managed switches allow you to operate multiple VLANs over a single connection.
If you setup additional VLANs, leave the traffic for the original/default LAN as __________ (tagged/untagged)
Untagged
with VLAN, what is trunking?
Network trunk links carry multiple VLAN traffic through a single cable
The network trunk is the uplink(s) to the router or other managed switches
T/F:
Every port on a managed switch has to be designated as either a Trunk Port or Access Port to use a VLAN.
True
What is a Trunk Port with VLANs?
Trunk ports pass tagged frames, with the exception of frames associated with the primary LAN (always untagged) that can still go through a trunk port with the tagged VLAN traffic
What is an Access Port with VLANs?
Access Ports only pass traffic for one specific VLAN
When to use Port Forwarding
Never. Use ONLY when no other remote access options are available.
Has no authentication, makes it easier to hackers to find these open ports.
What is a VPN?
Virtual Private Network
You can only connect to a VPN while outside the network that the VPN grants access to.
T/F
You should statically configure the WAN host?
False.
You should leave it as DHCP unless necessary for a specific assignment.
On the OSI Model, where do APs lie?
They operate at Layers 1 and 2
What is Frequency?
The peak-to-peak (or midpoint-to-midpoint) measurement, also called a “cycle”
Define Hertz
The number of “cycles” per second, or the measurement of “waves-per-second”
What is a radio signal Channel?
A channel is a designated radio frequency (wavelength) for the operation of a particular radio channel/TV station
What is co-channel interference?
When two devices are broadcasting on the same channel, their signals overlap and it’s hard to discern the separate information.
In networking, this interference results in a fluctuation/alternation of the broadcasts as each competes for communication on the same frequency.
With radio waves, there is a lack of precision, so another station in the same geographical area with the same frequency would lead to the radio picking up both broadcasts simultaneously (think old school radio dial scrolling)
What is adjacent channel interference?
When a second broadcast is on a nearby frequency, the two broadcasts would still overlap and interfere with the clarity of both stations.
In which frequency is adjacent channel interference more common: 2.4 or 5GHz?
2.4 GHz
5GHz is designed to not overlap.
Define SSID
Service-set Identifier = the network’s name
Should Band-Steering be turned on or off? Why?
Off, because it may try to force devices that can use both 2.4 and 5 GHz to run on the 5GHz band.
Further, every vendor implements it differently so it’s inconsistently implemented.
PCNA recommends disabling it.
What is best practice for wireless network passwords?
PCNA recommendation: 3 or 4 words strung together that the customer can easily remember
- Should >14 characters and should use a mix of upper and lower case letters
How wide is each 2.4GHz channel?
How many channels are in this band?
20MHz
11 total but they overlap. When selecting a channel, should use 1, 6, and 11 so they don’t overlap with their neighbor.
When building a wireless network, what three things do we have control over?
Channel selection
AP Placement
Transmit power
What channels and channel widths are available in UNII-1 and UNII-3 for the 5GHz wireless networking band?
UNII-1: channels 36-48
UNII-3: 149-161
Channels are 20MHz wide and designed to not overlap.
In wireless networking, what are the Dynamic Frequency Selection (DFS) channels and who uses them?
Channels 51-144, are often used by commercial and government radar systems.
When would be appropriate to use DFS channels in wireless networking?
Indoors with large buildings and campuses
Definitely not appropriate outdoors or with residential systems.
What is “data rate”?
The number of bits that can be transmitted in a second, usually measured in megabits.
Is an unattainable theoretical ideal, however, it does allow comparisons between APs.
What factors influence a wireless network’s data rate?
- The capabilities of the end device
- The number of streams between the device and the AP (number of antennas)
- Channel width (narrower = less data)
- Distance
- Interference
- Other factors
You can think of data rates for a wireless network like a funnel: at the top of the funnel is the advertised speed of the AP, but as data moves down the funnel, other factors begin to influence the data rate that is possible.
T/F
You should enable fast roaming when setting up an AP
True
It facilitates continuous connectivity by “pre-authenticating” a wireless device to all of the APs on a network once it has authenticated to one AP
Define Monitoring
It is the process of keeping status of networked devices and getting an alert when an important event occurs, such as traffic going offline
Define Management
The process of taking actions - either proactively or reactively - to configure systems and fix problems
Define Cloud Service
An online, hosted platform that allows dealers and technicians to provide service for customers
Which level of OvrC service allows you to manage the entire network and monitor every networked device at a site?
OvrC Pro
It is included on all Araknis routers
What is the name of the app that allows customers to mildly manage their network?
OvrC Connect
What feature is baked into most SnapOne networking-related products?
OvrC
What are the advantages of using an MPU in a network?
You can individually power off specific devices or turn them on in a specific sequence
You can schedule regular power cycles, and it can reboot devices if they fall offline
With Outlet Mode on an MPU, what is the only thing that should be selected for the network devices and why?
“Network Device (Reset Only)”
Accidentally powering off the connected network device remotely would result in a truck roll because you’ll no longer be able to remotely access the WattBox to turn them back on.
“Disabled” will power off the device and require a truck roll to power it back up
“Enabled” won’t power cycle
What three features are availble for use in OvrC only when using a managed power unit?
- Naming the outlets on the MPU
- Creating a schedule to reboot an outlet
- Enabling and configuring auto-reboot
What is power conditioning?
When a power conditioner can take the level of incoming electricity and stabilizes it so that the power to the connected device stays at a constant, optimal voltage
What is a power surge?
What are some example causes?
When significantly more voltage comes through wires into devices. They can degrade device performance, reducing its lifespan or killing it altogether.
Causes: lightning, wind, birds sitting on power lines
What do surge protectors do?
Safeguard equipment by limiting the amount of voltage that can pass through to the devices.
They force the incoming electricity through a series of resistors that decrease the voltage before it reaches the connected device.
When should surge protectors be replaced?
Every 3 years or after a lightning strike to the equipment/facilities in the local vicinity.
Every time a surge protector takes a hit from a surge, it loses some of its effectiveness.
UPS’s primary purpose?
To provide short term power to allow users to safely save any open files and to shut down the electrical devices to prevent damage when the power comes back on
In what order should network devices be powered on after a power outage?
Modem
Router
Core switch
Other devices
When troubleshooting a wireless network, what types of devices should you first check?
Provide examples.
The wired infrastructure:
- router
- each switch
- Ethernet cables
- and power supply (POE and plugs)
What are the three phases of successful network planning?
- Information gathering
- Design
- Implementation
Why is a customer interview important?
They can lead to key pieces of information specific to that project’s needs
You have a better idea of how the network will be used:
- number of devices
- daily routines
- habits
- priorities
Why is it important to have a floor plan?
Allow for marking-up the floor plans during the planning process
It’s good to have multiple copies of the floor plan if using paper, because you’ll inevitably go through multiple drafts
Why is it important to have site visits?
It allows you to assess the physical space:
- mark floor plans for cable runs
- identify sources of EMI and RFI
- see physical obstacles or potential WiFi interference
- identify where aesthetics may be of greater importance
- create device counts for each room
What is the proper order for network device planning?
Peripheral to Central
1) APs
2) Switches
3) Routers
4) MPUs
Considerations when choosing an AP
- Indoors or outdoors?
- Budget or performance?
- Customer’s aesthetic preferences and sensitivities
What is physical data rate?
The theoretical and unattainable throughput capacity of an AP
Is impacted by multiple factors, including:
- attenuation
- obstructions
- radio interferences
Define MU-MIMO
In reference to APs, is the antenna configuration
MU = multiple user
- allows multicast devices to communicate with an AP simultaneously
MIMO = multiple-input, multiple-output
- method for applying the capacity of a radio link usit multiple transmit and receive antennas
Define the term spacial diversity in wireless networking
The distance between the APs antennas causes each to receive the signal slightly differently
Often yields a a better signal for 4x4 because of all the variables of wireless:
- signal attenuation from building materials, sources of interference, etc.
What is network topology?
The layout that you choose for organizing switches together
*technically comprises every device, not just switches
What are the two main network topologies?
Star
- all devices connect to a central core switch
Hub and spoke:
- core switch and edge switches (allows to separate into zone-based smaller plans)
- Is really a compounded star topology
Key considerations for selecting a router?
- WAN speed requirements from the ISP
- WAN failover requirements
- LAN requirements
- Whether VLANs are needed
- What remote monitoring and management capabilities the project needs (e.g., is a VPN needed?)
- Size and complexity of the network
What is the proper order for implementing a network?
1) Power/MPU
2) Router
3) Switches (core switch then edge switches, no other devices quite yet)
4) APs (progressively so you can tune the devices as you bring them online)
5) Wired devices into the switches
*Is the opposite of the design process/Plan-the-LAN
What is WAN to LAN throughput?
The computing/processing power of the router
What needs to be considered when selecting an MPU?
1) Network and non-network devices
2) Managed power outlet needs
3) Power budget
4) Anticipate future expansion/growth
