Chapter 2 Review 2j5r6z

CHAPTER 2 (REVIEW QUESTIONS)

Q1.

Discuss the term “scalability.” What does it mean? Why is it an important network design goal? What are some challenges designers face when deg for scalability?

Ability of a system, network or process to be changed in size or to accommodate growth and expand business service to meet organization objectives. 1. management is able to see the value of making large amount of data available for customers, prospective customers, employees, vendors and suppliers 2. A scalable business model will stand a much larger chance of being profitable in the long run. Business needs to grow in order to be successful, and if your business isn’t prepared for that growth from an IT perspective, it can crash and burn. EXAMPLE: Say you spend money on a marketing campaign, driving potential new customers to your website. Traffic increases from 1000 hits a day to 10000 hits a day. If you aren’t ready for the massive increase in hits, your website may go down. Those potential customers will that your business has a broken website and will look to your competitors. 3. Scalability directly affects the major drivers or components of an organization such as Production, Distribution, Networks and Infrastructure.

4. Scalability is an important network design goal because it is an information technology service management (ITSM) principle of design, create, delivery, and management that meets the Information Technology Information Library framework (ITIL)

CHALLENGES: 1. Security 2. Delay and Delay Variations 3. Developers may underestimate the growth rate of an organization and may provide a budget that is underestimated to develop a scalable system.

4. Most large software systems (data centers/clouds) are distributed across many computers so the network can limit how scalable the software is if not designed properly. 5. Server affinity – server and client recognize previous sessions are marked as secure channel. This could pose a security threat with a new device or process introduced to the web farm. 6. Scalability could be a very difficult feature to integrate into a development phase, because it could require a total software change in the overall system architecture especially if the methodology used does not integration.

Q2.

A network design customer has a goal of 99.80 percent uptime. How much downtime will be permitted in hours per week? How much downtime will be permitted in minutes per day and seconds per hour? Which values are acceptable in which circumstances?

SLA level of 99.8 % uptime/availability gives following periods of potential downtime/unavailability:

Q3.

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Daily: 2m 52.8s

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Weekly: 20m 9.6s

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Monthly: 1h 27m 39.5s

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Yearly: 17h 31m 53.9s Assume you are in New York City in the United States and you are ing a 100-KB web page from a server in Cape Town, South Africa. Assume that the bandwidth Between the two cities is 1 Gbps. Which type of delay will be more significant, propagation delay or transmission delay? Defend your answer.

PROPAGATION DELAY: Propagation delay result from finite speed of light which is the time it takes a bit to propagate from one router to the next; it is a function of the distance between the two routers taking a long time to converge after a link outage due to routing protocols. Therefore transmission delay will be more significant; which is the time it takes to put digital data into a transmission line. (E.g. – 1024bytes packet on a 1.5444Mbps T1 Line = 5seconds) as compared to propagating signal through a fiber optics cable travelling approximately 2/3 the speed of light in a vacuum. Q4.

The chapter mentioned reconnaissance attacks. Do some research to learn more about the tools that attackers use when on a reconnaissance mission. In your own words, describe two tools that you researched.

Reconnaissance attack is an attempt to gain information about a targeted compters or networkds that can be used as a preliminary step toward a further attack seeking to exploit the target system. It could be ive or active. 1. Nmap: This tool is capable of detecting types of victim’s operating systems just using T fingerprinting. T fingerprinting uses advanced fingerprinting analysis of the T stack implementation. A T packet is crafted by switching on or off certain flags and sent to the remote machine, which allows the attacker make an intelligent guess of the operating system from its database of T stack signatures.

2. Traceroute: This tool is used to find out IP addresses of routers and firewalls that protect victim hosts. In case a firewall blicks UDP packets along the path. Other tools that can be used for active reconnaissance are

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Scanrand – Fast network scanner

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AMAP – Application Mapper

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Nessus – Vulnerability Scanner