Cisco Networking

Describe the 2 processes a daemon uses (listening and hears)?

"listening" for a request from a client, because they are programmed to respond whenever the server receives a request for the service provided by the daemon "hears" a request from a client, it exchanges appropriate messages with the client, as required by its protocol, and proceeds to send the requested data to the client in the proper format

What are the seven steps in a complete communication process?

1. Creation of data at the application layer of the originating source end device 2. Segmentation and encapsulation of data as it passes down the protocol stack in the source end device 3. Generation of the data onto the media at the network access layer of the stack 4. Transportation of the data through the internetwork, which consists of media and any intermediary devices 5. Reception of the data at the network access layer of the destination end device 6. Decapsulation and reassembly of the data as it passes up the stack in the destination device 7. Passing this data to the destination application at the Application layer of the destination end device

What 6 things do protocols define?

1. processes on either end of the communication 2. types of messages 3. syntax of messages 4. meaning of any informational fields 5. how messages are sent and the expected response 6. interaction with the nextlower layer

What are the 2 ports used and their purpose in FTP?

21- Used for control 20- Used for actual file transfer

Define a physical port

A connector or outlet on a networking device where the media is connected to a host or other networking device.

What is an internetwork?

A global mesh of interconnected networks (internetworks) meets these human communication needs.

What are the seven layers of the OSI Model?

Application, Presentation, Session, Transport, Network, Data Link, Physical

Which Layers of the OSI Model parallel with the TCP/IP Model?

Application, Presentation, Session-Application Transport-Transport Internet-Network Data Link, Physical-Network Access

What is the difference between an application and a service?

Applications interact with the user and services prepare data for the network

What are the benefits of using a layered model to describe networking?

Assists in protocol design, because protocols that operate at a specific layer have defined information that they act upon and a defined interface to the layers above and below. Fosters competition because products from different vendors can work together. Prevents technology or capability changes in one layer from affecting other layers above and below. Provides a common language to describe networking functions and capabilities.

What PDU is used when physically transporting the information over the medium?

Bits

What are the three primary functions of the Presentation Layer?

Coding and conversion of Application layer data to ensure that data from the source device can be interpreted by the appropriate application on the destination device. Compression of the data in a manner that can be decompressed by the destination device. Encryption of the data for transmission and the decryption of data upon receipt by the destination.

the visible components of the network platform

Computers (work stations, laptops, file servers, web servers) Network printers VoIP phones Security cameras Mobile handheld devices (such as wireless barcode scanners, PDAs)

What are the 3 layers of protocols described?

Content Layer, Rules Layer, Physical Layer

What is done at the Network Access Layer?

Controls the hardware devices and media that make up the network

What happens to emails in many companies once the email reaches the internal server?

Converted to a proprietary protocol for mail delivery

What are the 4 types of messages sent and received in DHCP?

DHCP Discover DHCP Offer DHCP Request DHCP Acknowledge

What is the PDU for the application layer?

Data

What is the process use at the receiving end called?

Decapsulation

What address does the network layer use?

Destination and source logical address

What addresses does the data link layer use?

Destination and source physical address

What does the transport layer use?

Destination and source process number (ports)

What is done at the Internet Layer?

Determines the best path through the network

What are the five aspects of the information network we will focus on in this course?

Devices that make up the network Media that connect the devices Messages that are carried across the network Rules and processes that govern network communications Tools and commands for constructing and maintaining networks

What does the command ipconfig /displaydns show?

Displays all of the cached DNS entries on a Windows XP or 2000 computer system

What do the upper layers use?

Encoded application data

What is the PDU for Layer 2 called

Frame

What is the PDU for the Network Access Layer?

Frame

What type of request is sent to the server when retrieving a web page?

GET

List and describe some of the commands used by the SMTP protocol.

HELO - identifies the SMTP client process to the SMTP server process EHLO - Is a newer version of HELO, which includes services extensions MAIL FROM - Identifies the sender RCPT TO - Identifies the recipient DATA - Identifies the body of the message

What protocol is used for secure transmission across the web?

HTTPS:

What address is used at Layer 3?

IP address

If the same request is made again where does the DNS server look?

In its cache

What happens if a DNS server does not have a name in its stored records?

It passes the request on to another DNS server

What is the layer 2 address called?

MAC address

What are the two processes that email servers perform?

MTA Mail Transfer Agent MDA Mail Delivery Agent

What is another name for an email application?

MUA Mail User Agent

What are the 3 primary types of media used in modern networks?

Metallic wires within cables Glass or plastic fibers (fiber optic cable) Wireless transmission

List examples of intermediary devices.

Network Access Devices (Hubs, switches, and wireless access points) Internetworking Devices (routers) Communication Servers and Modems Security Devices (firewalls)

What is the Network Access Protocol?

Network access protocols describe two primary functions, data link management and the physical transmission of data on the media.

Are peer-to-peer networks easy to secure?

No

What 2 Application Layer protocols are used in sending and receiving email?

POP (Post Office Protocol) and SMTP (Simple Mail Transfer Protocol)

What is the PDU for the Internet Layer?

Packet

What is the PDU of the Layer 3 information?

Packet

How is each application or service represented at Layer 4?

Port number

What do application layer protocols do?

Protocols provide the rules and formats that govern how data is treated.

List examples of process that intermediary devices perform.Regenerate and retransmit data signals

Regenerate and retransmit data signals Maintain information about what pathways exist through the network and internetwork Notify other devices of errors and communication failures Direct data along alternate pathways when there is a link failure Classify and direct messages according to QoS priorities Permit or deny the flow of data, based on security settings

What is done at the Application Layer?

Represents the data to the user plus encoding and dialog control

Which device decapsulates the frame at the edge of a network?

Router

What protocol is recommended alternative to Telnet when security is a concern?

SSH Secure Shell protocol

What is the Transport Layer PDU?

Segment

What are the three elements of communication?

Sender, Receiver, Chanel

What does the POST command do?

Sends information to the web server

What does the PUT command do?

Sends resources or content to the web server

Define an interface

Specialized ports on an internetworking device that connect to individual networks.

What are the 3 message types of SMB messages?

Start, authenticate, and terminate sessions Control file and printer access Allow an application to send or receive messages to or from another device

What is done at the Transport Layer?

Supports communication between diverse devices across diverse neworks

What are the two primary models used when describing networking?

TCP/IP and OSI

What criteria should be used to select network media?

The distance the media can successfully carry a signal. The environment in which the media is to be installed. The amount of data and the speed at which it must be transmitted. The cost of the media and installation

What process do networking layer protocol suites describe?

The format or structure of the message The process by which networking devices share information about pathways with other networks How and when error and system messages are passed between devices The setup and termination of data transfer sessions

What are the ways in which network infrastructure can vary?

The size of the area covered The number of users connected The number and types of services available

What does the physical layer do?

Timing and synchronization of bits

How is the protocol stack processed when sending information?

Top to bottom

When is a server declared to be an authoritative server?

When the resource is directly held on that server

What is an intranetwork?

a private connection of LANs and WANs that belongs to an organization, and is designed to be accessible only by the organization's members, employees, or others with authorization

What are peer-to-peer applications?

allows a device to act as both a client and a server within the same communication

What does Dynamic Host Confirmation Protocol (DHCP) do for a network?

allows a host to obtain an IP address dynamically when it connects to the network

What does the nslookup utility allow you to do?

allows the user to manually query the name servers to resolve a given host name

In general networking sense what is a server?

any device that responds to requests from client applications is functioning as a server

What do port numbers identify?

applications and Application layer services that are the source and destination of data

What are the two forms of software programs or process that provide network access in the Application Layer

applications and services

What is the main function of the session layer?

create and maintain dialogs between source and destination applications

What is the definition of the term network for this course?

data or information networks capable of carrying many different types of communications, including traditional computer data, interactive voice, video, and entertainment products.

What does the DNS protocol do?

defines an automated service that matches resource names with the required numeric network address.

What is an application protocol?

defines the content and formatting of the requests and responses exchanged between the client and server

What is File Transfer Protocol (FTP)?

developed to allow for file transfers between a client and a server

Define segmentation of messages

division of the data stream into smaller pieces

What is the definition of a host?

either the source or destination of a message transmitted over the network

What is the definition of a server?

hosts that have software installed that enables them to provide information and services

What is the definition of a client?

hosts that have software installed that enables them to request and display the information obtained from the server

Define the three parts of a url as listed on the page?

http:- protocol www.cisco.com- name of server web-server.htm- name of file or page

What does the information in the frame provide at Layer 4?

identifies the specific process or service running on the destination host device that will act on the data being delivered

What is the definition of a LAN?

individual network usually spans a single geographical area, providing services and applications to people within a common organizational structure

What is a Transport Protocol?

manages the individual conversations between web servers and web clients

What are the 2 advantages of segmentation?

many different conversations can be interleaved on the network segmentation can increase the reliability of network communications

What is the definition of a WAN?

networks that connect LANs in geographically separated locations

What would happen to the network if a message was sent as one massive continuous stream of bits?

no other device would be able to send or receive messages on the same network while this data transfer was in progress

What is proprietary?

one company or vendor controls the definition of the protocol and how it functions

What is multiplexing?

process used to interleave the pieces of separate conversations together on the network

What does the use of standards and protocols provide?

products from different manufacturers can work together for efficient communications

What are the two basic types of networking models?

protocol models and reference models

What does the Telenet application provide?

provides a standard method of emulating text-based terminal devices over the data network.

Define a NIC

provides the physical connection to the network at the PC or other host device.

What is the Internetwork Protocol

responsible for taking the formatted segments from TCP, encapsulating them into packets, assigning the appropriate addresses, and selecting the best path to the destination host.

What happens after the frame has reached its' destination?

the Layer 2 address information is removed as the data is decapsulated and moved up the protocol stack to Layer 3

What is the difference between a client and a server?

the device requesting the information is called a client and the device responding to the request is called a server

What do the Application Layer protocols of the TCP/IP protocol specify?

the format and control information necessary for many of the common Internet communication functions

What happens when the frame reaches the end device?

the frame and packet headers are removed and the data moved up to Layer 4

What do networking protocols describe?

the functions that occur during network communications

What does the application layer provide?

the interface between the applications we use to communicate and the underlying network over which our messages are transmitted

What do protocols provide?

the rules and formats that govern how data is treated

What is SMB (Server Message Block)?

the structure of shared network resources, such as directories, files, printers, and serial ports

What is hardware on a network?

the visible components of the network platform

What are application layer protocols used for?

to exchange data between programs running on the source and destination hosts

What are layer 3 devices primarily designed for?

to move data from one local network to another local network within an internetwork

What is a peer-to-peer network?

two or more computers are connected via a network and can share resources (such as printers and files) without having a dedicated server

What does a router do?

use the network identifier portion of this address to determine which path to use to reach the destination host