Chapter 1 (Network Models) - Mike Meyers Network+ (N01-007) Exam Guide

the MTU for a standard Ethernet frame

1518 bytes

A sublayer of the Data Link layer; it's the aspect of the NIC that talks to the systems operating system (via device drivers), provides flow control and handles multiple network protocols

Logical Link Control (LLC) Layer

delivers to every host on the network.

Broadcast

Layer 4 PDU; don't have a sequence number for each one that split up packets.

Datagram

Only has the destination and source ports, Length, Checksum and Data.

Datagram Fields

In a packet that gives the IPv4 address of the ultimate destination; it's 4 bytes long.

Destination IP Address Field

This 6-byte field is the identifier for the intended recipient, used in frames.

Destination MAC Address Field

The second set of six characters that make up a network device's MAC address. It's a unique serial number.

Device ID

Replaced MAC-48 as the numbering namespace for MAC Addresses.

EUI-48

The process of preparing data to go onto the network. Works down. Each layer adds more information so that the data gets to the correct recipient and the recipient knows what to do with the data.

Encapsulation

Broadcast MAC Address

FF-FF-FF-FF-FF-FF

Two systems on the same network can share the same IP address.

False

When the network interface card takes the packets and wraps them up and send them out along the medium to a layer two device. Layer 2 PDU.

Frame

4 bytes and uses CRC when receiving to verify data arrived intact, otherwise the frame is dropped. In the trailer.

Frame Check Sequence (FCS)

Data payload that was passed down from the application layer, maximum of 1500 bytes. 46 bytes minimum.

Frame Data Field

Layer 1 Device; is used to connect network segments together, but provides no traffic control. Basically a repeater and broadcasts to every port on the device.

Hub

32 bit address divided into four octets with octets ranging from 0 to 255.

IP Address

Who must be contacted to obtain MAC addresses for your NIC cards?

Institute of Electrical and Electronics Engineers (IEEE)

What OSI Layer does the TCP/IP protocol suite really begin?

Layer 3

The address for each node on an IP network used to deliver packets to the correct destination. Also known as an IP address.

Logical Address

Layer 3 Device; A device that transfers data from one network to another in an intelligent way. Makes transfer decisions based on IP addresses. Connect subnets together.

Router

Layer 4 PDU; have a sequence number for each one that split up packets.

Segment

Transport Layer PDU that has a Segment Number, Flags and Acknowledgement.

Segment Fields

Chunks of data chopped up before being sent on the network. Organizes and sends them to the NIC.

Segmentation

It's easier to see than in TCP/IP. Many operating systems represent a one using the combination of the IP address and port numbers for both sides of the TCP or UDP communication.

Session

How must an IP address be configured on a network?

Software

In a packet gives the IP address of the original source; it's 4 bytes.

Source IP Address Field

This 6-byte field identifies the frame's originating NIC or interface. Must be a unicast address.

Source MAC Address Field

What happens when a packet arrives at the destination subnet router?

Strips it from the frame then creates a new frame using the MAC Address of the destination IP address.

A logical subset of a larger network, created by an administrator to improve network performance or to provide security.

Subnet

Layer 2 Device; A computer networking device that connects network segments and filters by MAC address.

Switch

OSI Layers 5-7; Every app especially connection based must known how to initiate, control, and disconnect from a remote system. There's no one way, each has it's own method.

TCP/IP Application Layer

Automatically network aware and can talk to the network if they're in it and need it to function.

TCP/IP Applications

OSI Layer 3; TCP/IP model protocol that establishes internetworking. In the TCP/IP Model this is where routing takes place.

TCP/IP Internet Layer

OSI Layers 1 and 2; the TCP/IP techs depend on other techs to handle these network connections. Handles cabling, physical addresses, NICs and switches sit here. Deals solely in frames.

TCP/IP Link/Network Interface Layer

OSI Layer 4; Combines OSI model Transport and Session layers with a dash of Application. Deals a lot with segmentation and reassembly of data. It also defines other functions like connection or connectionless communication.

TCP/IP Transport Layer

After a NIC strips a frame, where does it send the data to?

the software

What happens to packets that weren't received in good order?

A request is sent for them.

How do you make programs network aware?

API

What kind of data does the physical layer handle?

Any

A mathematical algorithm that translates a file into a unique hexadecimal value compared with the Frame Check Sequence to verify data.

Cyclic Redundancy Check (CRC)

48 bit address divided into six two hex digit octets.

MAC Address

How many versions of the TCP/IP Model is there?

Many

A sublayer of the Data Link layer; creates and addresses frames. MAC. It adds or checks the FCS. Makes sure it's sent along network cabling.

Media Access Control (MAC) Layer

Copper wires, fiber optic wires and radio waves are considered what?

Methods of sending data.

a form of transmission in which a message is delivered to a group of hosts. Special groups must be made prior.

Multicast

What can operate on more than one OSI layer?

Multiple Protocols

Sends packets off to other services that knows how to handle them.

NIC Driver

What is the connection between the network hardware and software?

NIC Driver Software

Shows all running sessions.

Netstat -a command

Gives info on the session.

Netstat -n command

Interface between the PC and the network. Has a unique identifier known as a Media Access Control (MAC) address burned onto the ROM. Send binary data as pulses of electricity, light, or radio waves. All of them on the same network need to use the same frame type or they will not be able to communicate.

Network Interface Card (NIC)

a common set of rules to follow when creating networking hardware and software

Network Model

Create unique identifiers for each system and also create a set of communication rules for issues like how to handle data chopped up into multiple packets and how to ensure those packets get from one subnet to another.

Network Protocols

The seventh layer of the OSI model. The software using the data. May include functions such as encryption, user authentication and tools to control the look of data and are specific to the app. Actually refers to the code built into all OSes that enables network-aware apps.

OSI Application Layer

The second layer in the OSI model. Uses MAC Addresses to send a frame within the network. Has two sub-layers.

OSI Data Link Layer

The third layer of the OSI model. Routes packets according to IP addresses. Packets get created and addressed so they can go from one network to another.

OSI Network Layer

The lowest, or first, layer of the OSI model. Protocols in this layer generate and detect signals so as to transmit and receive data over a network medium.

OSI Physical Layer

The sixth layer of the OSI model. Responsible for managing and translating the information into an understandable format that the Application layer can process further. Taking datagrams and segments and turning them into formats programs can use.

OSI Presentation Layer

The fifth layer of the OSI model. It's software handles connecting applications to applications. Handles the sessions for a system; initiates sessions, accepts incoming sessions and opens and closes existing sessions.

OSI Session Layer

The fourth layer of the OSI model. Chunks of data can be much larger than the allowed packet size so they must be chopped up before being sent on the network. These can be segments or datagrams. Also initializes requests for packets that weren't received in good order.

OSI Transport Layer

When does the source NIC normally send out a broadcast to the network?

Obtaining a MAC address

Seven Layer Prescriptive Model; each layer defines an important function in computer networking and the protocols that operate at that layer offer solutions to those function.

Open Systems Interconnection (OSI) model

The first 24 bits of a MAC address, assigned to the NIC manufacturer by the IEEE.

Organizationally Unique Identifier (OUI)

A piece of test equipment used to view and measure a variety of different waveforms.

Oscilloscope

Layer 3 PDU; created and addressed so they can go from one network to another.

Packet

Data playload stored in a packet. %5

Packet Data Field

An actual address in the main memory device (NIC), it's 48 bits long. Also known as a MAC address.

Physical Address

Logical value between 1 and 65,536 assigned to specific applications or services.

Port

No longer important in TCP/IP. Standard formats are part and parcel with TCP/IP protocols and apps will know how to handle these formats.

Presentation

A set of rules, regulations, standards and procedures.

Protocols

What must the other system do with the incoming segmented packets?

Reassemble, Receive One Data Transmission, Verify Shape

Connection-based reliable transport layer protocol.

Transmission Control Protocol (TCP)

Different protocols from different manufacturers need to be well together so this gives each protocol a clear home in one of the four layers. It's a descriptive model

Transmission Control Protocol/Internet Protocol (TCP/IP) Model

Which of the following is not one of the three top level OSI protocols that make the TCP/IP application layer? A. Transport B. Session C. Presentation D. Application

Transport

Indicates the upper layer service contained in the frame. 2 Bytes.

Type Field

a form of message delivery in which a message is delivered to a single destination.

Unicast

Most commonly used network connections. Four pairs of wires to transmit and receive data.

Unshielded Twisted Pair (UTP)

Connectionless, unreliable transport layer protocol.

User Datagram Protocol (UDP)

Strips all the extra header information out of the data as it goes up the stack.

deencapsulation

Enables the MAC address information to be displayed from the command prompt.

ipconfig /all