NETACAD 17 BUILD A SMALL NETWORK

Question 1

What is the difference between large networks and small networks

Answer 1

Small networks typically have a single WAN connection provided by DSL, cable, or an Ethernet connection.

Large networks require an IT department to maintain, secure, and troubleshoot network devices and to protect organizational data. Managing a small network requires many of the same skills as those required for managing a larger one. Small networks are managed by a local IT technician or by a contracted professional.

Question 2

Explain the factors that must be considered when selecting network devices.

Answer 2

Cost

The cost of a switch or router is determined by its capacity and features. This includes the number and types of ports available and the backplane speed. Other factors that influence the cost are network management capabilities, embedded security technologies, and optional advanced switching technologies. The expense of cable runs required to connect every device on the network must also be considered. Another key element affecting cost considerations is the amount of redundancy to incorporate into the network.

Speed and Types of Ports/Interfaces

Choosing the number and type of ports on a router or switch is a critical decision. Newer computers have built-in 1 Gbps NICs. Some servers may even have 10 Gbps ports. Although it is more expensive, choosing Layer 2 devices that can accommodate increased speeds allows the network to evolve without replacing central devices.

Expandability

Networking devices are available in fixed and modular physical configurations. Fixed configuration devices have a specific number and type of ports or interfaces and cannot be expanded. Modular devices have expansion slots to add new modules as requirements evolve. Switches are available with additional ports for high-speed uplinks. Routers can be used to connect different types of networks. Care must be taken to select the appropriate modules and interfaces for the specific media.

Operating System Features and Services

Network devices must have operating systems that can support the organizations requirements such as the following:

Layer 3 switching
Network Address Translation (NAT)
Dynamic Host Configuration Protocol (DHCP)
Security
Quality of service (QoS)
Voice over IP (VoIP)

Question 3

What devices factor into the IP addressing scheme

Answer 3

End user devices - The number and type of connection (i.e., wired, wireless, remote access)
Servers and peripherals devices (e.g., printers and security cameras)
Intermediary devices including switches and access points

Question 4

What is the benefit of using a planned IP addressing scheme

Answer 4

makes it easier to identify a type of device and to troubleshoot problems, as for instance, when troubleshooting network traffic issues with a protocol analyzer.

Question 5

What are some ways of accomplishing redundancy

Answer 5

Redundancy can be accomplished by installing duplicate equipment, but it can also be accomplished by supplying duplicate network links for critical areas, as shown in the figure.

*Small networks typically provide a single exit point toward the internet via one or more default gateways. If the router fails, the entire network loses connectivity to the internet. For this reason, it may be advisable for a small business to pay for a second service provider as backup. Have a second router that is connected to another ISP

Question 6

Discuss traffic management in a small network

Answer 6

The routers and switches in a small network should be configured to support real-time traffic, such as voice and video, in an appropriate manner relative to other data traffic. In fact, a good network design will implement quality of service (QoS) to classify traffic carefully according to priority during times of congestion,

*Listed from highest priority to lowest
Voice, SMTP, Instant Messaging and FTP

Question 7

What is required to classify traffic according to priority?

Answer 7

QoS

Question 8

What are the two forms of software programs or processes that provide access to the network

Answer 8

network applications and application layer services.

Question 9

Describe network applications

Answer 9

Applications are the software programs used to communicate over the network. Some end-user applications are network-aware, meaning that they implement application layer protocols and are able to communicate directly with the lower layers of the protocol stack. Email clients and web browsers are examples of this type of application.

Question 10

Describe application layer services

Answer 10

Other programs may need the assistance of application layer services to use network resources like file transfer or network print spooling. Though transparent to an employee, these services are the programs that interface with the network and prepare the data for transfer. Different types of data, whether text, graphics or video, require different network services to ensure that they are properly prepared for processing by the functions occurring at the lower layers of the OSI model.

Each application or network service uses protocols, which define the standards and data formats to be used. Without protocols, the data network would not have a common way to format and direct data.

Question 11

What are some stipulations for using SSH

Answer 11

Network device - The network device (e.g., router, switch, access point, etc.) must support SSH to provide remote access SSH server services to clients.
Server - The server (e.g., web server, email server, etc.) must support remote access SSH server services to clients.

Question 12

Describe various network servers and their required related network protocols.

Answer 12

Web Server

Web clients and web servers exchange web traffic using the Hypertext Transfer Protocol (HTTP).
Hypertext Transfer Protocol Secure (HTTPS) is used for secure web communication.

Email Server

Email servers and clients use Simple Mail Transfer Protocol (SMTP) to send emails.
Email clients use Post Office Protocol (POP3) or Internet Message Access Protocol (IMAP) to retrieve email.
Recipients are specified using the user@xyz.xxx format.

FTP Server

File Transfer Protocol (FTP) service allows files to be downloaded and uploaded between a client and FTP server.
FTP Secure (FTPS) and Secure FTP (SFTP) are used to secure FTP file exchange.

DHCP Server

Dynamic Host Configuration Protocol (DHCP) is used by clients to acquire an IP configuration (i.e., IP address, subnet mask, default gateway and more) from a DHCP server.

DHCP Server

Dynamic Host Configuration Protocol (DHCP) is used by clients to acquire an IP configuration (i.e., IP address, subnet mask, default gateway and more) from a DHCP server.

Question 13

What do network protocols define to a network administrator?

Answer 13

Processes on either end of a communication session
Types of messages
Syntax of the messages
Meaning of informational fields
How messages are sent and the expected response
Interaction with the next lower layer

Question 14

Describe the factors that a small network administrator must consider when supporting real-time applications.

Answer 14

Infrastructure

The network infrastructure must support the real-time applications.
Existing devices and cabling must be tested and validated.
Newer networking products may be required.

VoIP

VoIP devices convert analog telephone signals into digital IP packets.
Typically, VOIP is less expensive than an IP telephony solution, but the quality of communications does not meet the same standards.
Small network voice and video over IP can be solved using Skype and non-enterprise versions of Cisco WebEx.

IP Telephony

An IP phone performs voice-to-IP conversion with the use of a dedicated server for call control and signaling.
Many vendors provide small business IP telephony solutions such as the Cisco Business Edition 4000 Series products.

Real-Time Applications

The network must support quality of service (QoS) mechanisms to minimize latency issues for real-time streaming applications.
Real-Time Transport Protocol (RTP) and Real-Time Transport Control Protocol (RTCP) are two protocols that support this requirement.

Question 15

What elements are required to scale a network?

Answer 15

Network documentation - Physical and logical topology
Device inventory - List of devices that use or comprise the network
Budget - Itemized IT budget, including fiscal year equipment purchasing budget
Traffic analysis - Protocols, applications, and services and their respective traffic requirements should be documented

Question 16

What should one do in order to determine traffic flow patterns

Answer 16

Capture traffic during peak utilization times to get a good representation of the different traffic types.
Perform the capture on different network segments and devices as some traffic will be local to a particular segment.

Question 17

Discuss the ping command

Answer 17

The ping command is the most effective way to quickly test Layer 3 connectivity between a source and destination IP address. The command also displays various round-trip time statistics.

Specifically, the ping command uses the Internet Control Message Protocol (ICMP) echo request (ICMP Type 8) and echo reply (ICMP Type 0) messages. The ping command is available in most operating systems including Windows, Linux, macOS, and Cisco IOS.

Question 18

Describe the IOS Ping indicators

Answer 18

Exclamation mark indicates successful receipt of an echo reply message.
It validates a Layer 3 connection between source and destination.

A period means that time expired waiting for an echo reply message.
This indicates a connectivity problem occurred somewhere along the path.

Uppercase U indicates a router along the path responded with an ICMP Type 3 “destination unreachable” error message.
Possible reasons include the router does not know the direction to the destination network or it could not find the host on the destination network.

Question 19

Describe the extended ping

Answer 19

A standard ping uses the IP address of the interface closest to the destination network as the source of the ping.
The Cisco IOS offers an “extended” mode of the ping command. This mode enables the user to create special type of pings by adjusting parameters related to the command operation.

Extended ping is entered in privileged EXEC mode by typing ping without a destination IP address.

Question 20

Describe TraceRoute

Answer 20

Traceroute can help locate Layer 3 problem areas in a network. A trace returns a list of hops as a packet is routed through a network. It is used to identify the point along the path where the problem can be found. In Windows, the command is tracert. In Cisco IOS the command is traceroute. There is also an extended traceroute command. It allows the administrator to adjust parameters related to the command operation

Question 21

Describe network baseline and give a potential way of starting one

Answer 21

One of the most effective tools for monitoring and troubleshooting network performance is to establish a network baseline. Creating an effective network performance baseline is accomplished over a period of time. Measuring performance at varying times and loads will assist in creating a better picture of overall network performance.

One method for starting a baseline is to copy and paste the results from an executed ping, trace, or other relevant commands into a text file. These text files can be time stamped with the date and saved into an archive for later retrieval and comparison.

Question 22

Describe the arp command

Answer 22

The arp command is executed from the Windows, Linux, or Mac command prompt. The command lists all devices currently in the ARP cache of the host, which includes the IPv4 address, physical address, and the type of addressing (static/dynamic), for each device.

Question 23

List various show commands and their function

Answer 23

show running-config

To verify the current configuration and settings

show interfaces

To verify the interface status and see if there are any error messages

show ip interface

To verify the Layer 3 information of an interface

show arp

To verify the list of known hosts on the local Ethernet LANs

show ip route

To verify the Layer 3 routing information

show protocols

To verify which protocols are operational

show version

To verify the memory, interfaces, and licences of the device

Question 24

Describe the show ip interface brief Command

Answer 24

One of the most frequently used commands is the show ip interface brief command. This command provides a more abbreviated output than the show ip interface command. It provides a summary of the key information for all the network interfaces on a router. The show ip interface brief command can also be used to verify the status of the switch interfaces

Question 25

Describe the six main steps in the troubleshooting process.

Answer 25

Step 1. Identify the Problem
This is the first step in the troubleshooting process.
Although tools can be used in this step, a conversation with the user is often very helpful.

Step 2. Establish a Theory of Probable Causes
After the problem is identified, try to establish a theory of probable causes.
This step often yields more than a few probable causes to the problem.

Step 3. Test the Theory to Determine Cause
Based on the probable causes, test your theories to determine which one is the cause of the problem.
A technician will often apply a quick procedure to test and see if it solves the problem.
If a quick procedure does not correct the problem, you might need to research the problem further to establish the exact cause.

Step 4. Establish a Plan of Action and Implement the Solution After you have determined the exact cause of the problem, establish a plan of action to resolve the problem and implement the solution.

Step 5. Verify Solution and Implement Preventive Measures
After you have corrected the problem, verify full functionality.
If applicable, implement preventive measures.

Step 6. Document Findings, Actions, and Outcomes
In the final step of the troubleshooting process, document your findings, actions, and outcomes.
This is very important for future reference.

Question 26

A technician is using the debug ip icmp privileged EXEC command to capture live router output. Which commands would stop this debug command on a Cisco router?

Answer 26

no debug ip icmp

undebub all

Question 27

A technician has established a remote connection to router R1 to observe debug output. The technician enters the debug ip icmp command then pings a remote destination. However, no output is displayed. Which command would the technician have to enter to display log messages on a remote connection

Answer 27

terminal monitor

Question 28

Describe duplex and the duplex communication modes

Answer 28

In data communications, duplex refers to the direction of data transmission between two devices.

There are two duplex communication modes:

Half-duplex - Communication is restricted to the exchange of data in one direction at a time.
Full-duplex - Communications is permitted to be sent and received simultaneously.

Question 29

Describe duplex mismatches

Answer 29

*Interconnecting Ethernet interfaces must operate in the same duplex mode for best communication performance and to avoid inefficiency anIf one of the two connected devices is operating in full-duplex and the other is operating in half-duplex, a duplex mismatch occurs. d latency on the link. While data communication will occur through a link with a duplex mismatch, link performance will be very poor

Question 30

Describe IP Addressing Issues on IOS Devices

Answer 30

IP address-related problems will likely keep remote network devices from communicating. Because IP addresses are hierarchical, any IP address assigned to a network device must conform to that range of addresses in that network. Wrongly assigned IP addresses create a variety of issues, including IP address conflicts and routing problems.

Two common causes of incorrect IPv4 assignment are manual assignment mistakes or DHCP-related issues.

Question 31

Describe default gateway issues

Answer 31

The default gateway for an end device is the closest networking device that can forward traffic to other networks. If a device has an incorrect or nonexistent default gateway address, it will not be able to communicate with devices in remote networks. Because the default gateway is the path to remote networks, its address must belong to the same network as the end device.

The address of the default gateway can be manually set or obtained from a DHCP server. Similar to IPv4 addressing issues, default gateway problems can be related to misconfiguration (in the case of manual assignment) or DHCP problems (if automatic assignment is in use).

Question 32

Describe DNS failure

Answer 32

DNS failures often lead the user to conclude that the network is down. If a user types in a domain name such as www.cisco.com in a web browser and the DNS server is unreachable, the name will not be translated into an IP address and the website will not display.