Section 2: Networking Flashcards

Question 1

Q

2.1 - Ports and Protocols - Introduction to IP

Series of moving vans

Answer

A

Efficiently move large amounts of data: Use a shipping truck
The network topology is the road: Ethernet, DSL, cable system
The truck is the Internet Protocol (IP): We’ve designed the roads for this truck
The boxes hold your data: Boxes of TCP and UDP
Inside the boxes are more things: Applicaton Information

Question 2

Q

2.1 - Ports and Protocols - Introduction to IP

TCP and UDP

Answer

A

Transported inside of IP: Encapsulated by the IP protocol
Two ways to move data from place to place: Different features for different applications
OSI Layer 4: The transport layer
Multiplexing: Use many different applications at the same time. TCP and UDP.

Question 3

Q

2.1 - Ports and Protocols - Introduction to IP

TCP - Transmission Control Protocol

Answer

A

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.

Question 4

Q

2.1 - Ports and Protocols - Introduction to IP

UDP - User Datagram Protocol

Answer

A

Connectionless: No formal open or close to the connection
“Unreliable” delivery: No error recovery. No reodering of data transmissions.
No flow control: Sender determines the amount of data transmitted. One-way communication

Question 5

Q

2.1 - Ports and Protocols - Introduction to IP

Why would you ever use UDP?

Answer

A

Real-time communication: There’s no way to stop and resend the data. Time doesn’t stop for your network.
Connectionless protocolas: DHCP (Dynamic Host Configuration Protocol) and TFTP (Trivial File Transfer Protocol)
The data might not get through: The application keeps track and decided what to do. It might do anything.
UDP is fast.

Question 6

Q

2.1 - Ports and Protocols - Introduction to IP

Communication using TCP

Answer

A

Connection-oriented protocols prefer a “return receipt”: HTTPS (Hypertext Transfer Protocol Secure) and 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.

Question 7

Q

2.1 - Ports and Protocols - Introduction to IP

Speedy delivery

Answer

A

The IP delivery truck delivers from one (IP) address to another (IP) address: Every house has an address, every computer has an IP address.
Boxes arrive at the house / IP address: Where do the boxes go? Each box has a room name.
Port is written on the outside of the box: Drop the box into the right room.
Port 80: web server unencrypted data (HTTP)
Port 443: web server encrypted data (HTTPS)
Port 25: mail server
Port 123: time server.

Question 8

Q

2.1 - Ports and Protocols - Introduction to IP

Lots of ports

Answer

A

IPv4 sockets: Server IP address, protocol, server application port number. Client IP address, protocol, client port number.
Non-ephemeral ports: Permanent port numbers. Ports 0 through 1023. Usually on a server or service.
Ephemeral ports: Temporary ports. Ports 1024 through 65,535. Determined in real-time by the client.

Question 9

Q

2.1 - Ports and Protocols - Introduction to IP

Port Numbers

Answer

A

TCP and UDP ports can be any numer between 0 through 65,535.
Most servers (services) use non-ephemeral port numbers. This isn’t always the case. It’s just a number.
Port numbers are for communication, not security.
Service port numbers need to be well known.
TCP port numbers aren’t same as UDP port numbers. TCP 80 is not the same as UDP 80.

Question 10

Q

2.1 - Ports and Protocols - Introduction to IP

Ports on the network

Answer

A

Web server - TCP/80
VoIP server - UDP/5004
Email server - TCP/143

Question 11

Q

2.1 - Ports and Protocols - Common Network Ports

Port Numbers

Answer

A

Well-known port number: Client and server need to match
Important for firewall rules: Port-based security
A bit of rote memorization: Becomes second nature after a while.
Make sure you know port number, protocol and how the protocol is used .

Question 12

Q

2.1 - Ports and Protocols - Common Network Ports

FTP - File Transfer Protocol

Answer

A

tcp/20 (active mode data), tcp/21(control): Transfers files between systems.
Authenticates with a username and password. Some systems use a generic/anonymous login
Full-featured functionality: List, add, delete, etc.

Question 13

Q

2.1 - Ports and Protocols - Common Network Ports

SSH - Secure Shell

Answer

A

Encrypted communication link - tcp/22
Looks and acts the same as Telnet.

Question 14

Q

2.1 - Ports and Protocols - Common Network Ports

Telnet

Answer

A

Telnet -Telecommunication Network: tcp/23
Loging to devices remotely: console access
In-the-clear communication (unencrypted): Not the best choice for production systems.

Question 15

Q

2.1 - Ports and Protocols - Common Network Ports

SMTP: Simple Mail Transfer Protocol

Answer

A

SMTP (Simple Mail Transfer Protocol): Server to server email transfer. tcp/25
Also used to send email from a device to a mail server. Commonly configured on mobile devices and email.
Other protocols are used for clients to receive email. - IMAP, POP3

Question 16

Q

2.1 - Ports and Protocols - Common Network Ports

DNS - Domain Name System

Answer

A

Converts names to IP addresses - udp/53: www.professormesser.com = 162.159.246.164
These are very crictical resources. Usually multiple DNS servers are in production.

Question 17

Q

2.1 - Ports and Protocols - Common Network Ports

DHCP - Dynamic Host Configuration Protocol

Answer

A

Automated configuration of IP address, subnet mask and other options: udp/67, udp/68. Requires a DHCP server. Server, appliance, integrated into a SOHO router etc.
Dynamic / pooled: IP addresses are assigned in real-time from a pool. Each system is given a lease and must renew at set intervals.
DHCP reservation: Addresses are assigned by MAC address in the DHCP server. Manage address from onle location.

Question 18

Q

2.1 - Ports and Protocols - Common Network Ports

HTTP and HTTPS

Answer

A

Hypertext Transfer Protocol: Communication in the browser. And by other applications.
In the clear or encrypted: Suppoted by nealy all web servers and clients.
HTTP: tcp/80. Hypertext Transfer Protocol. Web server communication.
HTTPS: tcp/443 Hypetext Transfer Protocol Secure. Web server communication with encryption.

Question 19

Q

2.1 - Ports and Protocols - Common Network Ports

POP3 / IMAP

Answer

A

Receive emails from server: Authenticate and transfer.
POP3 - Post Office Protocol version 3. tcp/110. Basic mail transfer functionality. Receive message for one email.
IMAP4 - Internet Message Access Protocess v4. tcp/143. Includes management of email inbox from multiple clients.

Question 20

Q

2.1 - Ports and Protocols - Common Network Ports

SMB - Server Message Block

Answer

A

Protocol used by Microsoft Windows: File sharing, printer sharing. Also called CIFS (Common Internet File System)
Using NetBIOS over TCP/IP (Network Basic Input/Output System): udp/137 - NetBIO name services (nbname). udp/139 - NETBIO session service (nbsession)
Direct over tcp/445 (NetBIOS-less): Direct SMB communication over TCP without NetBIOS transport.

Question 21

Q

2.1 - Ports and Protocols - Common Network Ports

SMNP - Simple Network Management Protocol

Answer

A

Gather statistics from network devices: Queries - udp/161. Traps - udp/162
v1 - The original: Structured tables. In-the-clear.
v2 - A good step ahead: Data type enhancements. Bulk transfers. Still in-the-clear.
v3 - A secure standard: Message integrity. Authentication. Encryption.

Question 22

Q

2.1 - Ports and Protocols - Common Network Ports

LDAP

Answer

A

LDAP (Lightweight Directory Access Protocol): tcp/389
Store and retrieve information in a network directory. Commonlu used in Microsoft Active Directory.

Question 23

Q

2.1 - Ports and Protocols - Common Network Ports

RDP - Remote Desktop Protocol

Answer

A

Share a desktop from a remote location over tcp/3389
Remote Desktop Services on many Windows versions
Can connect to an entire desktop or just an application
Clients for Windows, macOS, Linux, Unix, iPhone, Android, and others.

Question 24

Q

2.2 Network Devices

Network devices

Answer

A

Many different devices and components: All have different roles.
Some of these functions are combined together: Wirelss router/switch/firewall
Compare different devices: Understand when they should be used

Question 25

Q

2.2 Network Devices

Router

Answer

A

Routes traffic between IP subnets: Makes forward decisions based on IP address. Routers inside of switches sometimes called “layer 3 switches”
Often connects diverse network types: LAN, WAN, copper, fiber

Question 26

Q

2.2 Network Devices

Switches

Answer

A

Bridging done in hardware: Application-specific integrated circuit (ASIC). Forwards traffic based on data link (MAC) address
Many ports and features: The core of an enterprise network. May provide power over ethernet (PoE)
Multilayer switch: Includes routing functionality. Known as layer 3 switch.

Question 27

Q

2.2 Network Devices

Unmanaged devices

Answer

A

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.

Question 28

Q

2.2 Network Devices

Managed switches

Answer

A

VLAN support: Interconnect with other switch 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)

Question 29

Q

2.2 Network Devices

Access point

Answer

A

Not a wireless router: A wireless router is a router and an access point in a single device.
Asn access point is a bridge: Extends the wired network onto the wired network. Makes forwarding decisions based on MAC address.

Question 30

Q

2.2 Network Devices

Patch panels

Answer

A

Combination of punch-down blocks and RJ-45 connectors
Runs from desks are made once: Permanently punched down to patch pane.
Patch panel to switch can be easily changed. No special tools. Use existing cables.

Question 31

Q

2.2 Network Devices

Firewalls

Answer

A

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: Protects 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.

Question 32

Q

2.2 Network Devices

Power over Ethernet (PoE)

Answer

A

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.

Question 33

Q

2.2 Network Devices

PoE switch

Answer

A

Power over Ethernet: Commonly marked on the switch or interfaces.

Question 34

Q

2.2 Network Devices

PoE, PoE+, PoE++

Answer

A

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 part of the 802.3 standard. 25.5 DC power, 600 mA max current.
PoE++: IEEE 802.3bt-2018. 51 W (Type 3), 600 mA max current. 71.3 (type 4) , 960 mA max current. PoE with 10GBASE-T

Question 35

Q

2.2 Network Devices

Hub

Answer

A

“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

Question 36

Q

2.2 Network Devices

Cable modem

Answer

A

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 1Gigabit/s are available.
Multiple service: Data, voice, video

Question 37

Q

2.2 Network Devices

DSL modem

Answer

A

ADSL (Asymmetric Digital Subscriber Line): Use 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.

Question 38

Q

2.2 Network Devices

ONT

Answer

A

Optical network terminal: Fiber to the premises
Connect the ISP fiber network to the copper network: Demarcation poit (demarc) in the data center. Terminal box on the side of the building.
Line of responsibility: one side of the box is the ISP. The other side of the box is your networl.

Question 39

Q

2.2 Network Devices

Network Interface Card (NIC)

Answer

A

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 option: singel port, multi-port, copper, fiber.

Question 40

Q

2.2 Sofware Defined Networking

SDN (Softwar Defined Networking)

Answer

A

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.

Question 41

Q

2.2 Network Devices

SDN data flows

Answer

A

Between Application layer/ Management Plane: SSH, SNMP, API
Between Control layer / Control plane: Dynamic routing protocols
Between Infrastructure layer / Data plane: Network traffic.

Question 42

Q

2.3 Wireless Network Standards

Wireless Network Standards

Answer

A

Wireless networking (802.11): Managed by the IEEE LAN/MAN Standard Committee (IEE 802)
Many updates over time: Check with IEEE for the latest.
The Wi-Fi trademark: Wi-Fi Alliance handles interoperability testing

Question 43

Q

2.3 Wireless Network Standards

802.11a

Answer

A

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.

Question 44

Q

2.3 Wireless Network Standards

802.11b

Answer

A

Also an original 82.11 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 frequent conflict: Baby monitors, cordless phones, microwaves, ovens, bluetooth
Not commonly seen today.

Question 45

Q

2.3 Wireless Network Standards

802.11g

Answer

A

An “upgrade” to 802.11b. June 2003
Operaties 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 802.11b.

Question 46

Q

2.3 Wireless Network Standards

802.11n (Wi-Fi 4)

Answer

A

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.

Question 47

Q

2.3 Wireless Network Standards

802.11ac (Wi-Fi 5)

Answer

A

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)
Increaed channel bonding: Larger bandwith usage.
Denser signaling modulaation: Faster data transfers.
Eight MU-MIMO downlink streams: Twice as many streams as 802.11n. 6.9 gigabits per second
Maximum theortetical throughput per stream is 867 Mbit/s

Question 48

Q

2.3 Wireless Network Standards

802.11ax (Wi-Fi 6)

Answer

A

Approved in 2021. The successor to 802.11ac/Wi-Fi 5
Operates at 5 GHz and / or 2.4 GHz: 20, 40, 80, and 160 MHz widths.
1,201 megabits per second per channel: A relatively small increase in throughput. Eight bi-directional MU-MIMO stream.
Orthogonal frequency-division multiple access (OFDMA): Works similar to cellular communication. Improves high–density installations.
Maximum theoretical throughput of 9.6 Gbit/s

Question 49

Q

2.3 Wireless Network Standards

Long-range fixed wireless

Answer

A

Wireless access point in a house with the stock antennas. You might get a range of 40 to 50 meters.
Try connecting two buildings located miles from each other: Fixed directional antennas and increased signal strength.
Outdoors: Minimal signal absorption or bounce.
Directional antennas: Focused, point-to-point connection.
Wireless regulations are complex. Refer to your country’s regulatory agency.
Frequency use: Unlicensed 2.4 GHz or 5 GHz frequencies. Addtional frequencies may be availanle. Additional licensing may be requiree.
Signal strength: Indoor and outdoor power is usually regulated.
Outdoor antenna installation is not trivial. Get an expert. Be safe.

Question 50

Q

2.3 Wireless Network Standards

RFID (Radio-frequency identification)

Answer

A

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.

Question 51

Q

2.3 Wireless Network Standards

NFC (Near Field Communication)

Answer

A

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.

Question 52

Q

2.3 - Wireless Network Technologies

802.11 technologies

Answer

A

Frequency: 2.4 GHz or 5 GHs 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.

Question 53

Q

2.3 - Wireless Network Technologies

Band selection and bandwidth

Answer

A

2.4 GHz spectrum for 802.11 - North America: Channels 1, 6 and 11
5 GHz spectrum for 802.11 - North America. Has more channels and bandwidth.

Question 54

Q

2.3 - Wireless Network Technologies

Bluetooth

Answer

A

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 communicated over 100 meters.

Question 55

Q

2.4 - Network Services

DNS server

Answer

A

Domain Name System: Converts names to IP addresses. And vice versa
Distributed naming system: The load is balanced across many different servers
Usually managed by the ISP or enterprise IT departement. A critical resource.

Question 56

Q

2.4 - Network Services

DHCP server

Answer

A

Dynamic Host Configuration Protocol: Automatic IP address configuration
Very common service. Available on most home routers.
Usually running on central servers.

Question 57

Q

2.4 - Network Services

File server

Answer

A

Central storage of documents, spreadsheets, video, pictures, and any other files. A fileshare
Standard system of file management: SMB (Server Message Block) for Windows, Apple filiing protocol (AFP) for Apple.
The front-end hides the protocol: Copy, delete, rename, etc.

Question 58

Q

2.4 - Network Services

Printer server

Answer

A

Connect a printer to the network: Provide printing services for all network devices.
May be software in a computer: Computer is connected to the printer.
May be built-in to the printer: Newtork adapter and software.
Uses standard printing protocols. SMB (Server Message Block), IPP (Internet Printing Protocol), LPD (Line Printer Daemon).

Question 59

Q

2.4 - Network Services

Mail server

Answer

A

Store your incoming mail. Send your outgoing mail.
Usually managed by the ISP or the enterprise IT departement. A complex set of requirements.
Usually one of the most important service. 24/7 support

Question 60

Q

2.4 - Network Services

Syslog

Answer

A

Standard for message logging: Diverse systems, consolidated log
Usually a central logging server. Integrated into the SIEM
You’re going to need a lot of disk space. No more. More than that.

Question 61

Q

2.4 - Network Services

Web server

Answer

A

Respond to browser requests: Using standard web browsing protocols - HTTP/HTTPS. Pages are built with HTMLS and HTML5
Web pages are stored on the server: Downloaded to the browser. Static pages or built dynamically in real-time.

Question 62

Q

2.4 - Network Services

Authentication server

Answer

A

Login authentication to resources: Centralized management
Almost always an enterprise service. Not required on a home network.
Usually a set of redundanct servers. Always available. Exteremely important service.

Question 63

Q

2.4 - Network Services

Spam

Answer

A

Unsolicited messages: email, forums, etc.
Various content: commercial advertising, non-commercial proselytizing, p hishing attempts.
Significant technology issue: Security concerns, resource utilization, storage costs, managing th spam.

Question 64

Q

2.4 - Network Services

Spam gateways

Answer

A

Unsolicited email: Stop it at the the gateway before it reached the user.
On-site or cloud-based.

Answer 65

A

Next-generation firewall, Unified Threat Management (UTM)/ Web Security gateway
URL filter / content inspection
Malware inspection
Spam filter
CSU/DSU
Router, Switch
Firewall
IDS/IPS
Bandwidth shaper
VPN endpoint.

Answer 66

A

Distribute the load: Multiple servers. Invisible to the end-user.
Large-scale implementations: Web server farms, database farms.
Fault tolerance: Server outage have no effect. Very fast convergence.

Answer 67

A

Configurable load: Manage across servers.
TCP Offload: Protocol overhead
SSL offload: Encryption/ Decryption
Caching: Fast response.
Prioritization: QoS
Content switching: Application-centric balancing.

Answer 68

A

An intermediat server: Client makes the request to the proxy. The proxy performs the actual request. The proxy provide results back to the client.
Useful features: Access control, caching, URL filtering, content scanning.

Answer 69

A

Supervisory Control and Data Acquisition System: Large-scale, multip-site industrial control system (ICS)
PC manages equipment: Power generation, refining, manufactuting equipment, facilities, industrial, energy, logistics.
Distributed control system: Real-time informtion, system control
Requires extensive segmentation: No access from the outside.

Answer 70

A

Legacy systems: Another expression for “really old”. May also be “really important”. Learning old things can be just as important as learning the new things.
Embedded systems: Purpose-built device. Not usual to have direct access to the operating system
Alarm system, door security, time card system.

Answer 71

A

Appliances: Refrigerators
Smart devices: Smart speakers respond to voice commands.
Air control: thermostats, temperature control
Access: Smart doorbells.
May require a segmented network: Limit any security breaches.

Answer 72

A

IPv4 is the primary protocol for everything we do. Included in almost all configurations.
IPv6 is now part of all major operating systems. The backbone of our internet infrastructure.

Answer 73

A

Internet Protocol version 4: OSI Layer 3 address. Since one byte is 8 bits, the maximum decimal value for each byte is 255.
8 bits = 1 byte = 1 octect.
32 bits = 4 bytes.

Answer 74

A

Internet Protocol v6 - 128-bit address. 340 undecillion.
Your DNS is very important!
First 64 bits is generally the network prefix (/64)
Last 64 bits is the host network address.

Answer 75

A

IP Address, e.g., 192.168.1.165. Every device needs a unique IP address
Subnet mask, e.g., 255. 255. 255.0: Used by the local device to determine what subnet it’s on. The subnet mask isn’t (usually) transmitted across the network. You’ll ask for the subnet mask all the time. What’s the subnet mask of this network?
Default gateway, e.g. 192.168.1.1: The router that allows you to communicate outside of your local subnet. The default gateway must be an IP address on the local subnet.

Answer 76

A

We remember name: professormessor.com, google.com, youtube. com
Internet routers don’t know names. Router only know IP addresses.
Something has to translate between names and IP addresses. Domain Name Service.
You configure two DNS servers in your IP configuration. That’s how important it is.

Answer 77

A

IPv4 address configuration used to be manual: IP address, subnet mask, gateway, DNS servers, NTP servers, etc.
October 1993 - The bootstrap protocol.
BOOTP didn’t automatically define everything. Some manual configuations were still required. BOOTP also didn’t know when an IP address might be available again.
Dynamic Host Configuration Protocol (DHCP): Initially released in 1997, updated through the years. Provides automatic address / IP configuration for almost all devices.

Answer 78

A

DORA: A four-step process
Discover: Find a DHCP server
Offer: Get an offer
Request: Lock in the offer
Acknowledge: DHCP server confirmation

Answer 79

A

DHCP assigns an IP address from the first available from a large pool of addresses. Your IP addres will occasionally change.
You may not want your IP address to change. Server, printer, or personal preference.
Disable DHCP on the device: Configure the IP address information manually. Require additional administration.
Better: Configure an IP reservation on the DHCP server. Associate a specific MAC address with an IP address.

Answer 80

A

No DHCP server reservations. You configure the IP address manually.
Difficult to change later. You must visit the device again.
A DHCP reservation is preferable. Change IP address from the DHCP server.

Answer 81

A

Also called a linked-local address. No forward by routers.
IETF has reserved 169.254.0.0 through 169.254.255.255: First and last 256 addresses are reserved. Functional block of 169.254.1.0 through 169.254.254.255
Automatically assigned: Uses ARP to confirm the address isn’t currently in use.

Answer 82

A

Translates human readable names into computer-readable IP addresses. You only need to remember www.Professormesser. com
Heirarchical. Follow the path
Distributed database: Many DNS servers. 13 root server clusters (Over 1000 actual server). Hundreds of generic top-level domains (gTLDs) -.com, .org, .net, etc.
Over 275 country code top-level domains (ccTLDs) -.us, .ca, .uk, etc.
TLD is top-level-domain

Answer 83

A

dig
nslookup

Answer 84

A

Resource Records (RR): The database records of domain name services.
Over 30 record types: IP adddresses, certificates, host alias names, etc.
These are important and critical configurations. Make sure to check your settings, backup, and test!.

Answer 85

A

Defines the IP address of a host. This is the most popular query
A records are for IPv4 addresses: Modify the A record to change the host name to IP address resolution.
AAAA records are for IPv6 addresses. The same DNS server, different records.

Answer 86

A

Determines the host name for the mail server. This isn’t an IP address. It’s a name.

Answer 87

A

Human-readable text information: Useful public information. Was originally designed for informal information.
Can be used for verification purposes: If you have access to the DNS, then you must be the administrator of the domain name.
Commonly used for email securtiy. External email servers validate information from your DNS.

Answer 88

A

dig professormesser.com txt

Answer 89

A

nslookup -type=txt professormesser.com

Answer 90

A

SPF protocol: A list of all servers authorized to send emails for this domain. Prevent mail spoofing. Mail servers perform a check to see if incoming mail really did come from an authorized host.

Answer 91

A

Digitally sign a domain’s outgoing mail: Validated by mail servers, not usually seen by the end user. The public key is in the DKIM TXT record.

Answer 92

A

Domain-based message authentication, reporting, and conference (DMARC): Prevent unauthorized email use (spoofing). An extension of SPF and DKIM
You decide what external email servers should do with email that don’t validate throught SPF and DKIM. That policy is written into a DMARC TXT record. Accept all, send to spam, or reject the email. Compliance reports can be sent to the email administrator.

Answer 93

A

IP address range. And excluded addresses
Subnet mask
Lease durations
Other scope options: DNS server, Default gateway, VOIP servers

Answer 94

A

Grouping of IP addresses: Each subnet has its own scope. 192.128.1.0/24, 192.128.2.0/24,192.128.3.0/24
A scope is generally a single contiguous pool of IP addresses. DHCP exceptions can be made inside of the scope.

Answer 95

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Dynamic assignment: DHCP server has a big pool of addresses to give out. Addresses are reclaimed after a lease period.
Automatic assignment: Similar to dynamic allocation. DHCP server keeps a list of past assignments. You’ll always get the same IP address.

Answer 96

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Address reservation. Administratively configured.
Table of MAC (Media access control) addresses: Each MAC address has a matching IP address.
Other names: Static DHCP assignment, static DHCP, static assignment, IP reservation.

Answer 97

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Leasing your address: It’s only temporary. But it can seem permanent.
Allocation: Assigned a lease time by the DHCP server. Administratively configured.
Reallocation: Reboot your computer. Confirm the lease.
Workstation can also manually release the IP address. Moving to another subnet.

Answer 98

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T1 timer: Check in with the lending DHCP server to renew the IP address. 50% of the lease time (default).
T2 timer: If the original DHCP server is down, try rebinding with any DHCP server. 87.5% of lease time.

Answer 99

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Local Area Networks: A group of devices in the same broadcast domain.

Answer 100

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Virtual Local Area Networks: A group of devices in the same broadcast domain. Separated logically instead of physically. SIngle switch instead of multiple.

Answer 101

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Local Area Networks: A group of devices in the same broadcast domain.

Answer 102

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Virtual Private Networks: Encrypted (private) data tranversing a public network
Concentrator: Encryption/decryption access devide. Often integrated into a firewall.
Many deployment options: Specialized cryptographic hardware. Software-based options available.
Used with client software: Sometimes built into the OS.

Answer 103

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On-demand access from remote device. Software connects to a VPN concentrator.
Some software can be configured as always on.

Answer 104

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Communication to a satelite. Non-terrestrial communication
High cost relative to terrestrial networking: 50 Mbit/s down, 3 Mbit/s are common. Remote sites, difficult-to-network sits.
High latency: 250 ms up, 250 ms down. Starlink advertises 40 ms and is working on 20 ms.
High frequencies - 2 GHz. Line of sight. Rain fade.

Answer 105

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High speed data communication. Frequencies of light.
Higher installation cost than copper: Equipment is more costly. More difficult to repair. Communicate over long distances.
Large installation in the WAN core: Supports very high data rates. SONET, wavelenth division multiplexing.
Fiber is slowly approaching the premises. Business and home use.

Answer 106

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Broadband: Transmission across multiple frequencies. Different traffic types.
Data on the “cable: network: DOCSIS (Data Over Cable Service Interface Specification)
Multiple services: Data, voice, video.

Answer 107

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ADSL (Asymmetric Digital Subscriber Line). Uses telephone lines.
Download speed is faster than the upload speed. (asymmetric) : 200 Mbit/s downstream / 20 Mnit/s upstream are common. 10,000 foot limitation from the central office (CO). Faster speeds may be possible if closer to the CO.

Answer 108

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Mobile devices: “cell” phones
Separate land into “cells”: Antenna coverages a cell within certain frequencies.
Tethering: Turn your phone into wireless router.
Mobile hotspot: Standalone devices. Use your phone for other things. .

Answer 109

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Wireless Internet Service Provider: Terrestrial internet access using wireless
Connect rural or remote locations. Internet access for everyone
Many different deployment technologies: Meshed 802.11, 5G home internet, Proprietary wireless.
Need an outdoor antenna. Speeds can range from 10 to 1000 megabits per second.

Answer 110

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Local Area Network: Local is relative
A building or group of buildings: High-speed connectivity
Ethernet and 802.11 wireless: Any slower and it isn’t “local”

Answer 111

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Wide Area Network: Spanning the globe
Generally connects LANs across the distance: And generally much slower than the LAN
Many different WAN technologies: Point-to-point serial, MPLS, ect. , terrestrial and non-terrestrial

Answer 112

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Personal Area Network: Your own private network. Bluetooth, IR, NFC
Automobile: Audio output, integrate with phone.
Mobile phone: Wireless headset
Health: Workout telemetry, daily reports.

Answer 113

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Metropolitan Area Network: A network in your city. Larger than a LAN, often smaller than a WAN
Historically MAN-specific topologies: Metro Ethernet
Common to see government ownership. They “own” the right-of-way.

Answer 114

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Storage Area Network (SAN): Looks and feels like a local storage device. Block-level access. Very efficient reading and writing.
Requires a lot of bandwidth: May use an isolate network and high-speed network technologies.

Answer 115

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Wirelss LAN: 802.11 technologies.
Mobility: Within a building. In a limited geographical area.
Expand coverage additional access points; Downtown are. Large campus.

Answer 116

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“Pinch” the connector onto a wire: Coaxial, twisted pair, fiber
Connect the modular connector to the ethernet cable: The final step of the process
Metal prongs are pushed throught the insulation: The plug is also permanently pressed onto the cable sheath.

Answer 117

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Get a good crimper: And a good pair of electrician’s scissors / cable snips. And a good wire stipper.
Make sure you use the correct modular connectors: Differences between the wire types.
Practice, practice, practice. It won’t take long to becoming proficient.

Answer 118

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Wireless networks are increadibly easy to monitor: Everyone “hears” everything.
Purpose-built hardware or mobile device add-on: Specializes in 802.11 analysis.
Identify errors and interferences: Validate antenna locaton and installation.

Answer 119

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Tone generator: Toner probe. Where does that wire go? Follow the tone
Tone generator: Puts an analog sound on the wire.
Inductive prone: Doesn’t need to touch the copper. Hear through a small speaker.

Answer 120

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Easy wire tracing: Even in complex environments.
Connect the tone generator to the wire: Modular jack. Coax. Punch down connectors.
Use the probe to locate the sound: The two-tone sound is easy to find.

Answer 121

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“Punch” a wire into a wiring block: 66 block, 110 block, and others.
Can be tedious: Every wire must be individually punched.
Trims the wires during the punch. Very efficient process.

Answer 122

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Organization is key: Lots of wires. Cable management.
Maintain your twists: Your category 6A cable will thank you later.
Document everything. Writted documentation. Tags. Graffiti.

Answer 123

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Relatively simple: Continuity test. A simple wire map
Can identiy missing pins: Or crossed wires
Not usually used for frequency testing: Crosstalk signal loss, etc.

Answer 124

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Useful for testing physical ports: Or fooling your applications.
Serial / RS-232 (9 pin or 25 pin)
Network connections: Ethernet, T1, Fiber
These are not cross-over cables.

Answer 125

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Intercept network traffic: Send a copy to a packet capture device
Physical taps: Disconnect the link, put a tap in the middle. Can be an active or passive tap
Port mirror: Port redirection, SPAN (Switched Pot ANalyzer). Software-based tap. Limited functionality, but can work well in a pinch.