Key words Flashcards
What is Layer 1 of the OSI model?
Physical layer - Signalling, Cabling, Connectors
What happens at Layer 1 (Physical layer) of the OSI model?
Packets are converted into electrical, radio, or optical pulses and transmitted as bits (the smallest possible units of information) over wires, radio waves or cables
What does a layer 1 (Physical) issue look like?
Issues with cabling, Punch downs, Electrical signals, Bad ports - Solutions can involve replacing cables, Swapping adapter cards
What is Layer 2 of the OSI model?
Data link Layer - The basic network ‘language’ - Foundation layer of connection - Uses MAC address on ethernet
What happens at Layer 2 (Data link) of the OSI model?
Handles communications between devices on the same network. If Layer 3 is like the address on a piece of mail, then layer 2 is like indicating the office number or apartment of that address. Ethernet is the protocol most used here.
What is DLC protocol and what does it do?
Data link control protocol - Provides functions such as flow control, error detection and error control
What is Layer 3 of the OSI model?
Network layer
What happens at Layer 3 of the OSI model?
Handles the routing and sending of data between different networks. The most important protocols at this layer are IP and ICMP. IP addresses (Logical Address) operates at this layer.
What is Layer 4 of the OSI model?
Transport Layer
What happens at Layer 4 of the OSI model?
Provides the means for transmitting data between the two connected parties, as well as controlling the quality of service. The main protocols used are TCP and UDP - Assembling and Disassembling data happens here
What is TCP?
What is the connection type?
Does it sequence data?
Does it allow for data retransmission?
Is delivery guaranteed?
Does it check for errors?
Does it support broadcasting?
Is it fast or slow?
Transmission Control Protocol:
Connection type - Requires an established connection before transmitting data
Data Sequence - Can sequence data (send in a specific order)
Data retransmission - Can retransmit data if packets fail to arrive
Delivery - Delivery is guranteed
Check for errors - Thorough error-checking guarantees data arrives in its intended state
Broadcasting - Not supported
Speed - Slow but complete data delivery
TCP is the only protocol that can retransmit lost data packets - When reliability is critical, TCP is the best option.
What is UDP?
What is the connection type?
Does it sequence data?
Does it allow for data retransmission?
Is delivery guaranteed?
Does it check for errors?
Does it support broadcasting?
Is it fast or slow?
User Datagram Protocol:
Connection type - No connection is needed to start and end a data transfer
Data Sequence - Cannot sequence or arrange data
Data retransmission - No data retransmitting. Loss data can’t be retrieved
Delivery - Delivery is not guaranteed
Check for errors - Minimal error-checking covers the basics but may not prevent all errors
Broadcasting - Supported
Speed - Fast, but at risk on incomplete data delivery
Name some use cases that TCP is better suited to?
Email or Texting
File transfers
Web browsing
Remote device or network administration
Name some use cases that UDP is better suited to?
Live streaming
Online gaming
Video chatting/ Conferencing
VOIP
Domain Name Systems
How does TCP work?
Uses the 3 way hand shake
Client device initiating contact will send a sequence number (SYN) to the server. Tells the server the number that the data packet transfer should begin with.
The server acknowledges the client SYN and sends its own SYN number. This step is referred to as SYN-ACK (SYN acknowledgement)
The client then acknowledges(ACK) the server’s SYN-ACK, which forms a direct connection and begins the data transfer.
The connection between the sender and receiver is maintained until the transfer is successful. Every time a data packet is sent, it requires an acknowledgment from the receiver. So, if no acknowledgment is received, the data is resent.
If an error is acknowledged, the faulty packet is discarded and the sender delivers a new one. Heavy traffic or other issues may also prevent data from being sent. In that case, the transmission is delayed (without breaking the connection).Thanks to these controls, successful data delivery is guaranteed with TCP.
How does UDP work?
UDP works by sending data immediately to the receiver who made a transmission request until the transmission is completed or terminated. Sometimes called a “fire and forget” protocol, UDP fires data at a recipient without confirming delivery or checking if packets arrived as intended.
Does not perform a handshake. Speeds up transfer data by sending packets without making an agreement with a receiver.
What is layer 5 of the OSI model?
Session Layer
What happens at layer 5 of the OSI model?
Controls connections between computers (this can also be handled at layer 4 by the TCP protocol) - Part of the host that makes connection to the remote host i.e. a web browser to a web server or an email client to to an email server.
What is layer 6 of the OSI model?
Presentation Layer
What is EMI?
Electromagnetic Interference
What is CSMA/CD?
Carrier Sense Multiple Access/Collision Detection Is a technology used for devices to listen and see who is communicating. Collision detection
What is ARP?
Address resolution protocol - ARP is a method used to get the MAC address of hosts
What is full duplex?
Is a communication mode where two devices can talk at the same time
What is CSMA/CA?
Is for collision avoidance rather than detection
What is a SFP(Small form-factor Pluggable)?
SFP is a type of transceiver that connects to a MSA module slot on the motherboard to allow any fiber connector to be used with any switch
What is a Punchdown tool?
What is a 110-block?
What is the MDF?
Main Distribution Frame
What is the IDF?
Intermediate Distribution Frame
What is the first thing to check if your machine cannot ping anything on the network including another machine on your subnet?
Check if the NIC has a link light
How many inches is a U?
1.75
Which type of Radio grade is the most common for Coaxial cable?
RG^
What is the broadcast address for ARP?
FF:FF:FF:FF:FF:FF
Which command will show the ARP cache?
arp -a
Name the different IP class ranges and the ranges?
Class A = 0-126
Class B=128-191
Class C = 192-223
Class D = 224-239
Many users are complaining that they cannot get on the Internet. You arrive at one user’s computer and ping the company’s Router and it’s successful. What would be the next command you should type?
netstat
nslookup
net use
tracert
netstat
nslookup
net use
tracert
You are using netstat, and you want to show all Active Ports. What would you type?
netstat -n
netstat -o
netstat -b
netstat -a
A
netstat -a
Explanation:
-n = Will show Foreign Addresses in a Numerical Format (Cleans up the Report)
-b = Shows the executable for every connection.
-o = Will show the Process ID column.
-a = Shows all ACTIVE/OPEN Ports.
What port does HTTP use?
20
80
143
443
80
What is the proper name for a DNS server that can respond to a query with their own DNS information?
Authoritative
Administrative
Authenticated
Admissible
Authoritative
Which type of record is used with IPv4?
AAAA Record
CNAME
MX
A Record
A record
A=IPv4
AAAA=IPv6
CNAME=Alias
MX=Mail Exchange Servers
Which of the following is NOT part of the Structured Cabling System?
Horizonal Runs
Wall Jacks
Equipment Room
Work Area
Wall Jacks
You type www.google.com and you receive an error. However, if you type a known IP address for Google, it works. What might be the problem?
DHCP Scope Issue
Misconfigured IP Address
Incorrect Default Gateway
DNS
DNS (Domain Name System)
Explanation:
DNS = Resolves FQDN to IP Addresses
Which tool is used for testing DNS using a third-party tool?
dig
nslookup
ping
netstat
DIG - Used on Apple Mac and Linux
What is an example of Authentication?
Accessing a Folder you were granted rights to?
Showing an ID
Proving through Credentials that you have rights to a System.
Using a Retinal Scanner
Proving through credentials that you have rights to a system
What are the 3 Methods of Security Access to a System?
Identification, Authentication, Authorization
Identification, Automating, Authorization
The “Three Ps” - Proof, Proper Rights, and Proper Access
Authorization, Authentication, Accessibility
Identification, Authentication, Authorization
Which would be an example of Role-Based Access control?
Logging in with a Username and Password to Access a System
Assigning Rights to a Folder based on a User
Labeling a Resource with a specific Name that would provide Access
Placing an “Owner” Label on a User Account
A
Assigning Rights to a Folder based on a User
Explanation:
Role Based is assigning users and groups specific rights to specific resources.
Authentication is Logging in with a Username and Password
Mandatory Access Control is Labeling a Resource with a Specific Name that would provide Access
Discretionary Access Control is placing an “Owner” Label on a User Account
Which of the following is a benefit of Virtualization?
It allows you to create more efficient VPNs
Hardware consolidation
It’s very expensive, but worth the price
It can run on very low-end computers
Hardware consolidation
What is Network Function Virtualization (NFV)?
network functions virtualization replaces the functionality provided by individual hardware networking components. This means that virtual machines run software that accomplishes the same networking functions as the traditional hardware
You have an application that you are developing, but you don’t want the hassle of setting up servers, ACLs, backups, and managing them. Which type of cloud service would you use?
Software as a Service (SaaS)
Platform as a Service (PaaS)
Infrastructure as a Service (IaaS)
Infrastructure as Code (IaC)
Platform as a Service (PaaS)
When discussing Infrastructure as Code (IaC), what does automation mean?
Using code to provision and maintain systems in a consisten manner.
Creating pipelines that automate using longer sequences.
Automatically updating services using Windows Update
Running several instances of an application automatically.
Using code to provision and maintain systems in a consistent manner
Big Corp’s data center has a fiber and cable ISP. What aspect of security does this represent?
Active-Passive
Multipathing
Redundancy
Clustering
Redundancy
What is a VLAN?
What is an SSID?
A service set identifier (SSID) is a sequence of characters that uniquely names a Wi-Fi network.
With VoIP, which Port does Session Initiation Protocol (SIP) use?
3389
5060/5061
143
80
5060/5061
Which policy describes what users can and cannot do with company equipment?
Acceptable Use Policy (AUP)
Non-Disclosure Agreement (NDA)
BYOD Policy (Bring Your Own Device)
Memorandum of Understanding (MOU)
Acceptable Use Policy
The CIA Model is a basic model for security. What does CIA stand for?
Confidentiality, Integrity, and Availability
Central Intelligence Agency
Confidentiality, Intelligence and Accessibility
Computers, Intelligence, Adaptibility
Confidentiality, Integrity and Availability
Which would be an example of a Denial of Service (DoS) Attack?
Masquerading
Opening tons of Web Browser pages on a Computer
VLAN Hopping
Ping Flood
Ping Flood
What is SNMP?
Simple Network Management Protocol
What is an ethernet frame composed of?
FCS, Data, ACK, Sequence, Source Port, Destination Port, Source IP Address, Destination IP Address, Source Mac, Destination
What is an IP packet composed of?
Data, Ack, Sequence, Source Port, Destination, Source IP Address, Destination IP Address - Everything an ethernet frame is composed of minus the FCS and the MAC Addresses
What does PDU stand for?
Protocol Data Units
What does BGP stand for?
Border Gateway Protocol
What does CRC stand for and what does it do?
What are the first 3 pairs of numbers of MAC addresses known as?
OEM numbers - Original Equipment Manufacturer
What is a MAC Address?
It is a 48-bit identifier for a NIC
How do NICs decide whether or not to process a frame?
They use MAC addresses to identify if the frame is for them
How many values of an IP address will definitely apply to all machines on a network?
The first 3 values
When a router receives an ethernet frame, what does it strip?
The MAC addresses and the FCS - Leaving the IP Packet
What does a Router use to know where to send data?
Routing Table
What does a router do?
Connects multiple Local Area Networks
What are the first 1024 port numbers known as?
Well known ports
What is Port 80?
HTTP
What is Port 20+21?
FTP
Why are port numbers used?
They help direct packet traffic between the source & destination - To ensure data goes to the correct application
Why do packets have sequence numbers?
So that the network software can reassemble the file correctly
What are the advantages of coaxial cable?
Highly resistant to electromagnetic interference - (EMI)
Highly resistant to physical damage
What are the disadvantages of Coaxial cable?
Inflexible
Expensive
What does the Radio Grade specify?
The thickness of the conductors, insulation & shielding
What does UTP stand for?
Unshielded Twisted Pair
What is the maximum distance of a UTP cable?
100 Metres (325 feet)
What is the standard max bytes of an ethernet frame?
1522 bytes
What is the max bytes that a jumbo frame can contain?
9000 bytes
What cable type has the least amount of fire resistance?
PVC
What is plenum and plenum rate cable?
Plenum is the gap between the drop ceiling and actual ceiling - Plenum rated cable is designed to be run in plenum - Has the highest fire rating cladding on cable and highest fire rating
What is riser rated cable?
Cable designed to run between the different floors in a building, less fire rating than plenum-rated cable but more fire protection than PVC
What are the most commonly used cables in networks?
Straight through cables
What do switches use to forward packets or frames?
MAC addresses/MAC table
What is S.O.A?
Start of Authority - Is the primary DNS server for a particular zone
What is CNAME?
Canonical name - Alias
What does a reverse lookup zone do?
Used to resolve IP addresses to FQDN’s - Primarily used for Mail servers
What does a domain name server do?
Resolve IP addresses to FQDN’s
What is VRRP and what does it do?
What is FHRP and what does it do?
What is interior routing and what does it do?
