CompTIA Network+ (N10-009)

Transmission Control Protocol (TCP)

Reliable way to send segments across networks. Two way information.

A fundamental protocol within the Internet protocol suite that consists of is set of rules that govern the exchange of data

The way hand shake

SYN, SYN-ACK, ACK.

User Diagram Protocol (UDP)

Connectionless protocol. Unreliable.

TCP Data

Segments

UDP data

Datagram

Layer 4 Data Type

segments

UDP is useful for

Audio and video

Windowing

Allows the clients to adjust data in each segment

Buffering

Occurs when devices allocate memory to store segments if bandwidth is not readily available.

Layer 4 devices

TCP and UDP

WAN accelerators

Load balancers

Firewalls (blocking ports and firewalls)

Session layer

Keeps conversation separate to prevent intermingling data

Set up session

Checking user credentials and assigning numbers to sessions to help identify them.

Maintain session

Data transfers back and forth across the network

Tear down session

Ending of a session after the transfer is done or when the other party disconnects.

Layer 5 devices

H.323

NetBIOS

H.323

Used to set up, maintain, and tear down voice and video connections.

RTP (Real-time Transport Protocol)

Streaming Audio or video. Two way format like phone call or FaceTime.

NetBIOS

Used to share files over a network.

Presentation Layer

Formats the data to be exchanged and secures that data with proper encryption.

Data formatting or encryption

Layer 6 (presentation)

Data formatting

Dara is formatted by the computer to have compatibility between different devices.

American Standard Code for Information Interchange (ASCII)

Text-based language to use.

GIF, JPEG, and PNG

A type of Data format

Encryption

Used to scramble the data in transit to keep it secure from prying eyes and provide data confidentiality.

TLS (Transport Layer Security)

A security protocol that uses certificates and public key cryptography for mutual authentication and data encryption over a TCP/IP connection.

Layer 6 things

Scripting languages

Standard text

Pictures

Movie files

Encryption algorithms

Application Layer (Layer 7)

Provides application level services where users communicate with the computer (file transfer, network transfer)

Application services

Unites communicating components from more than one network application.

Service advertisement

Sending out of announcements to other devices on the network to state the service they offer.

Email application

Web browsing

Domain name service

File transfer protocol

Remote access

Layer 7

Physical Layer (Layer 1)

Where transmission of bits across the network occurs and includes physical and electrical network characteristics.

Physical layer data

bits

Transmission Modulation

If it changes during the clock cycle, then a 1 is represented (otherwise, a 0 is represented)

True or false: cables are also part of the physical layer

True

Cross over cable flips transmission

True

Straight through cable flips transmission

False

Asynchronous

Uses start and stop bits to indicate when transmissions occur from the sender to the receiver.

Synchronous

Uses a reference clock to coordinate the transmission by both sender and receiver.

Broadband

Devices bandwidth into separate channels

Baseband

Uses all available frequencies on a medium(cable) to transmit data.

Time Division Multiplexing (TDM)

each session takes a turns using time slots, to share the medium between all users.

Statistical Time Division Multiplexing (STDM)

Dynamically allocates the time slots in an as needed basis.

Frequency Division Multiplexing (FDM)

Divides the medium into channels based on frequencies and each session is transmitted over a different channel.

Multiplexing

Enables simultaneous usage of a baseband connection by multiple users

Fiber optic

Ethernet cable

Coaxial cable

Bluetooth

Wi-fi

NFC

Hubs

Access points

Media converters.

Layer one devices

True or false: Layer one devices essentially repeat and pass along what is received

True

Data Link Layer (Layer 2)

Packages data into frames and transmits those frames on the network.

Datalink layer data type

Frames.

Media Access Control (MAC)

Physical addressing system of a device which operated on a logical topology.

Each letter of a MAC address is how many bits

4 bits.

First 24-bits of a MAC address(6 digits)

Vendor code

The last 24 bits of the MAC address.

Unique value

Logical link control (LLC)

Provides connection services and allows acknowledgement of receipt of receipt of messages.

Isochronous

Network devices use a common reference clock source and create time slots for transmission.

Network interface cards

Bridges

Switches

Layer 2 data link layer

Packet Switching

Data is devices into packets and then forwarded.

Circuit switching

Dedicated communication link is established between two devices.

Message switching

Data is devices into messages which may be stored and then forwarded.

Route Discovery and Selection

Manually configured as a static route or dynamically through a routing protocol.

Connection services

Augment layer 2 connection services to improve reliability.

Internet Control Message Protocol (ICMP)

Sends error messages and operational information to an IP destination.

Routers

Multi layer switches

IPV4/IPV6

ICMP

Layer 3

Encapsulation

The process of putting headers (and trailers) around some data.

Protocol Data Unit (PDU)

A single unit of information transmitted in a computer network

SYN(synchronization)

Used to synchronize connection during the three way handshake.

ACK (acknowledgment)

Used during the three way handshake, but also used to acknowledge the successful receipt of packets.

FIN (Finished)

Used to tear down the virtual connection created using the three way handshake and the SYN flag.

RST(Reset)

Used when a client or server receives a packet that it was not expecting during the current connection.

PSH (Push)

Used to ensure data is given priority and it processed at the sending or receiving ends.

URG(urgent)

Similar to PSH and identified incoming data as urgent.

TCP has a 20 bite header

True

UDP has a 29 byte header

False it has an 8 byte header.

EtherType

Used to indicate which protocol is encapsulated in the payload of a frame.

Wireshark

Packet analyzer than can pull apart some network traffic and show different layers of the OSI model

Port

A virtual entry/exit point for communications used by software applications to exchange information.

A logical opening in a computer that represents a service or application.

Protocol

A set of rules and conventions for data exchange between network devices.

Well-known port numbers

0-1023

Registered Port Numbers

1024-49151

Ephemeral ports

Short-lived temporary ports which are opened for just a small period of time from a predefined range of ports.

True or false: TCP uses a three-way handshake to establish a connection.

True

Windowing

Occurs by allowing the receiver to specify the amount of data it can handle at a time

TCP uses packetization, acknowledgment and error checking to ensure data integrity

True

User Datagram Protocol (UDP)

A communication protocol used across the Internet for especially time sensitive transmission.

Internet control message protocol (ICMP)

Integral part of the Internet protocol suite which is a set of networking protocols used on the Internet.

What does an ICMP message consist of

Type, code, and checksum.

ICMP flood attack

Type of attack that involves overwhelming a target machine with a large number of ICMP echo request packets. (Aka ping packets)

distributed denial-of-service (DDoS) attack

Where the attacker usually uses a network of compromised computers (called a botnet) to generate a significant amount of traffic.

Ping of death

attack that exploits a vulnerability that existed in older, unpatched systems where the attacker sends malformed or oversized packets using the ICMP protocol.

Port 80

Hypertext Transfer Protocol (HTTP)

Hypertext Transfer Protocol (HTTP)

An application layer protocol that enables plain text communication between clients and servers.

Port 443

Hypertext Transfer Protocol Secure (HTTPS)

Difference between HTTP and HTTPS

Security and encryption, default usage, and search engine optimization (SEO) and trust.

True or false: Port 443 with SSL/TLS encryption for HTTPS provides more security than HTTP

True

What type of communication is SMTP, POP3, and IMAP

Email communication.

Simple Mail Transfer Protocol (SMTP)

Standard protocol used for sending emails across the Internet and operates over Port 25

SMTP Port

Port 25

SMTPS

Port 465 and port 587

Post Office Protocol version 3 (POP3)

Used to retrieve emails from a remote server to a local client over port 110

POP3

Port 110

Internet Message Access Protocol(IMAP)

Operates over Port 143 and allows users to manage emails directly on the email server.