Network Design Methodology Assignment Questions

Subject Name : Networking

Final Exam Questions

Q1. What are the merits of using the top down network design methodology versus the bottom up In your answer, assume that the reader knows little of either method. (Marked out of 5)
Top down network design methodology has been recommended to the networking professionals so as to cater the problems related to the complex networks. According to Oppenheimer (2011), the top-down methodology begins at the upper layers of the OSI reference model. It focuses on the applications, sessions and data transport before selecting routers and switches which are responsible for the functions at the lower layers. It first explores organisational groups and their structures so as to identify the relevant group of people whom the organisation is serving. The top down network design methodology is iterative. It first gathers the view of customers requirements. With the increase in number of users, network related issues and problems also increase. Certain cases where customers are looking for quick response to a network design, designers believe that they are aware of the customers requirements and they end up missing important expectations of the customers. Unexpected scalability and performance problems are few such issues which can be addressed using top-down approach. The method performs requirement analysis prior selecting the technology thus it solves the problems with the appropriate solution. The advantage of the top down network design methodology is that it recognizes that logical change and physical design are subject to change when information related to customers increases.
Q2. How are data traffic and information flow analyzed (Marked out of 5)
Efficient data traffic and information analysis provides sufficient information in order to troubleshoot network issues and handling and preventing unauthorized activity on the network. To analyse information flow and data traffic firewall is placed in the path from the intranet web server. The firewall analyses the network traffic that is directed towards the web server. HTTP port 80access has been given to all the users using firewall. It is due to unrestricted intended traffic for port 80. The benefit of the firewall is that it restricts the network packets entering from a different service and they are never forwarded to the web server. It is important to note that the network segments are different from the web administrators (Bonaventure, 2011). Deep packet network traffic analysis identifies bottleneck in the network along with the applications which are acting as a barrier for resources and bandwidth. The flow-based network traffic analysis tool provides top-level information including IP address and traffic volumes. It also helps in analyzing activities on websites, users, applications and hosts files. By analyzing the network traffic each activity on the network is identified which helps in improving the performance and security of the network.
Q3. Explain the purpose of routing in a network. (Marked out of 5)
Router is an important component in a computer network as it facilitates the movement of data packets. These data packets move from one network to another and from one device to another. Security to the network is an additional benefit of integrating routing in a network. Routing has been designed to route data from one node to another node of the network. Network has variable sizes and complexities. TCP/IP is a routing design is developed to do the same. It supports the transfer of the data which is concerned about the identified networks without considering the status of nodes in the network (Velte amp Velte, 2014). TCP/IP has multiple protocols which enables TCP/IP protocol to manage data flow between the networks. Routers also help in connecting multiple network segments but they are different from bridged devices. Bridges, on the other hand, operate on the basis of the information contained within the 802.3 data frame. They are also unaffected by the routing protocols that are being run over the network. Routers perform at the network protocol level and simultaneously forward network traffic as per the information stored within the data frame. This information is then forwarded from one network segment to another.
Q4. Why is a star topology network easier to trouble shoot in comparison to a bus topology (Marked out of 5)
The start topology does not allow the data packets to move from excessive number of nodes. The topology only allows 3 devices and 2 links which can be involved in communication between two devices. Each of the devices is isolated with its link connecting it to the hub making it an individual device. Such individual devices are straightforward and are also able to disconnect each it with the other devices. The individual devices that are isolated also prevent non-centralised failure to affect the network. Chances of increase in size of the network also rise due to connection of additional devices and increase in capacity. It happens when the central hub is bottleneck and its capacity increases. As per Bonaventure (2011), centralization also makes the inspection of the traffic through the network easy and suspicious behaviour of the traffic can also be analysed. Start topology, due to its network characteristic is easy to trouble shoot. Centralization is the biggest advantage of the topology which makes analysis of the traffic easy. It does not complexity like other networks rather fault detection is easy in this topology. Unlike Bus topology, in which every time a new node is added, entire network gets disrupt. The traffic flow and traffic analyses become complicated and so is the troubleshooting. On the other hand, in star topology, isolation and centralization makes fault detection easy. Each link and device can be investigated individually making fault detection simple.
Q5. Explain the purpose of Simple Network Management Protocol (SNMP). (Marked out of 5)
Simple Network Management Protocol (SNMP) is an application layer protocol. It is a software device which is used to monitor network and managing devices such as PC, router, switches and servers. SNMP is quite simple but advantageous for the organisation as it helps the organisation to manage networks. It enables the system to change, reset passwords remotely, re-configuring IP addresses. It is possible due to its reading and writing abilities. It also provides information on how much bandwidth is being used, and error reports in the log so that troubleshooting can be done as per the identified trends. Alert for low disk space, monitoring servers CPU and memory use is generated due to SNMP. When a device gets failed, an error message is send by the application (Bonaventure, 2011). Another advantage of the SNMP application is that its monitoring stations keeps on tracking devices for their status in every few minutes, which is also known as active polling. Along with this, passive SNMP devices keep sending alerts to the monitoring station whenever there is an error condition identified. It uses UDP as the transport protocol and if the management traffic traverses the firewalls its default ports get open.
Q6. Describe the physical characteristics of the most common type of Ethernet cabling, the connectors it uses, and the reason it is used. (Marked out of 5)
Ethernet cable is the form of network cable that is used on wired network. They are used within the local area network like PC, routers and switches. There are different types of Ethernet cables which are created to optimize performance on certain tasks. Ethernet cables are manufactured in two forms, solid and stranded. Solid Ethernet are considered better and improved than the stranded as they are able to provide protection against electrical interference (Velte amp Velte,
2014). They have a length of 324 feet for CAT5 cable and 700 feet for CAT 6. Disadvantage of the Ethernet cable is that they might lose network when they pass any electrical appliance which is a concern when they are quite lengthy. These are generally used on business networks where wires are manned inside the walls, under tables and are fixed on the floors. However, stranded Ethernet cables are less prone to wearing and tearing and are considered ideal for home networks or while the user is mobile. Wi-Fi and Bluetooth have replaced Ethernet on a vast business and home network due to advantages of wireless network over Ethernet cables.
Q7. Describe what the Physical layer of the OSI represents. (Marked out of 5)
According to Bonaventure (2011), physical layer is the layer 1 in the OSI model. It is the lowest layer and responsible for sending bits from one system to another. The layer is not concerned about the meaning of the bits and deals and has a physical connection to the network in order to manage transmission and reception of signals. Physical layer performs several functions including representation of bits, synchronization, line configuration, etc. data in the physical layer consists of stream bits which should be encoded into signals for transmission. It also defines encoding of 0 and 1 when they are converted into signals. Physical layer directly communicates with the actual communication media and which represents bit values in different ways. This requires specific protocols for each media type so that various qualities of the physical medias attachment interface.
Q8. Which OSI layer addresses something that you can touch (Marked out of 5)
Physical layer is the actual hardware which is used to transmit signals over media. In the physical layer two communicating devices are linked in a physical medium such as electrical cable, optical fiber, or wireless as well. According to Bonaventure (2011), electrical cable and optical fiber are physical components that are touched wireless is a network that is signaled to run a system. To transmit the information over different types of electrical cables, component of physical layer is used. Most commonly known electrical cables are twisted pairs used in telephone network, and coaxial cables used in cable TV. Optical fibers are also used in public and enterprise networks. These physical devices are used when the distance between the communication devices is more than one kilometer. Optical fiber also has two types, multimode and monomode. Monomode fibers are limited to a distance of few kilometers while multimode is used for distances more than several ten kilometers.
Q9. Identify the situations in which single-mode and multi-mode fiber optic are used. (Marked out of 5)
There are various cables available which transmits lights. Basic differences between cables are done on the basis of their length and diameters. Single and multimodal are example of optical fibre which is commonly used. Use of application determines the appropriate fibre optic. As oer Bonaventure (2011), single mode optical fibre allows only one mode of light within a given time. The light reflection developed due to passing of the light reduces attenuation and enabling the ability for the light signal to travel further. It is ideal for long distances which require more bandwidth. Multimodal optical fibre has large diametrical core which allows more than one modes of light o pass through it. It allows number of light to pass through the mode. These are generally used for short distances such as LAN, audio and video applications.
Q10. Provide a brief explanation addressing why the OSI model is referred to as a reference model (Marked out of 5)
With the increase complexity of computer networks, network researchers have proposed various models to describe characteristics and services of various networks. Open System Interconnection (OSI) model is one such model and it is also considered as the simplified version of the reference model. The reference model is generally divided into five layers. Starting from the Physical Layer, Datalink Layer, Network Layer, Transport Layer and Application Layer are other four layers in the reference model. The OSI model has seven layers including the above mentioned four layers. The OSI model is considered as a refined reference model. It is so because it has divided application layer further in three layers, the Session Layer, the Presentation Layer and the Application Layer. The OSI Application layer has several generic service elements. TCP/IP is also a reference model but it has placed Presentation and Session layers in the Application Layer.
Q11. Describe network switching. (Marked out of 5)
According to Velte amp Velte (2014), network switching is the process of channelizing data received from an input port so that it can be transmitted to the desired destination. Data entering a port is referred as ingress and exiting the port is referred as egress. Switch is the medium through which the data is transmitted to its final destination. There are different types of switching as well, circuit switching, and packet switching and multi protocol label switching. Circuit switching takes place between two parties which comes are connected within a physical network. Packet switching breaks down the messages into small components called packets and then transmit these packets on intermediate network devices. Multi protocol label switching (MPLS) is used in the traditional layer when packets are routed to their destinations. In MPLS each routing device takes independent decision.
Q12. A network administrator is considering placing a firewall on an external file server in the network. What is the purpose of the firewall, and is it important for the firewall to be stateful (Marked out of 5)
To provide computer networks protection against network elements such as denial of service attacks, intrusions, etc. It keeps a check on the inbound and outbound data packets so as to determine to allow the connection. Tracking of the source and destination port numbers, sequence numbers and source and destination IP addresses are done by stateful firewall. Without making firewall inside of the network cannot be protected from the outside network. It is also important to that firewall must be modified in order to connect traffic with web server via port 80. This requires web server to have its own firewall. Firewalls are enabled to perform deep packet inspection which also increases protocol vulnerabilities. It is generally placed between trusted and untrusted network. Trusted network is the internal network whereas untrusted network is an external network. Firewall is placed between public network and the internal network where all incoming traffic is considered untrusted, hence required to be inspected by the firewall. NAT or Pat are also configured at the firewall to handle the translation taking place between private IP address and the public IP addresses. However, firewall is not the end to end solution.
Q13. What is the first consideration that a network architect should have when designing a network for a customer Briefly explain your reasoning. (Marked out of 5)
The first consideration of the network architect is virtual LAN at the Ethernet level. The site must ascertain the critrea of the sort of Internet connection (Dordal, 2018). The architectural design should provide four important choices namely point to point, hub, mesh and ring, that describe the migration of the data between the systems. If the customer is using network technologies such as voice over IP and streaming server of media, it would impact the performance of the Local area network. Point to point architecture is the simplest architecture to set up and to manage. The ring architecture is slightly older than other architectures that would provide the solutions that are most significant and complex to manage. SONET has been used while monitoring the data through private lines.
Q14. Explain the role of network security. (Marked out of 5)
Network security plays an important role in saving the stack buffer overflow and heap buffer overflow. The security is associated with the preventive measures in saving the networking infrastructure from misuse and unauthorized access to the data. The security looks into the creation of the secure platform for the users as well as programmers. Some examples of the cyber insecurity are the access gained by the Kernal on the email account of yahoo by looking into the information of forgotten the password. The authenticate access is a major issue associated with the cyber security (Dordal, 2018). To mitigate the authorized access there should be encryption in the data files and documents that have been addressed through secure hashes namely SSH and TLS. The network security is an important part of the internet because the unauthorized data can be used by the hackers in the negative ways that can lead to the inefficiency and fraud in the given condition.
Q15. Explain the Transmission Control Protocol/Internet Protocol suite. (Marked out of 5)
Transmission Control Protocol/Internet Protocol suite consist of the lower level specifications that would include the primary application of the electronic mail, file transfer as well as terminal emulation. TCP/IP suit associated with the OSI model illustrates the relation between the OSI model and the referencing model. The role played by each layer is refers ad the document of the inter-networking basis. In the recent time TCP/IP suite are being implemented with the help of the multivendor protocol. The support for the suit is available to every vendor of the computer (Cisco Systems Inc, 2015). TCP/IP is a primary suite used for the communication between the interconnected networks. It can also be used for the communication through the private network that can be internal or external.
Q16. Briefly describe the similarities and differences between a hub and a switch.
(Marked out of 5)
The hub sent the data to the to all the nodes of the computers and devices that are connected to the hub but a switch sent data to the nodes as and when required , it shows that the switch is smarter than the switch (Bonaventure, 2011). Both the hub and the switch are the part of the Ethernet. Hub transfer the data to the nodes but the switch address the destination first then sent the data t the node. Both the hub and the switch are the networking devices that store the data in the form of topology. The hub works in the star topology whereas the switch can complement the communication between any pair of the given ports. The hub belongs to the similar type of collision domain whereas the switch belongs to the different types of collision domain. The hub operates in the physical layer where as the switch operates in the data link layer. The hub uses the broadcast transmission whereas the switch use multicast, multicast a well as broadcast type of the transactions. There is no provision of filtering in the hub that is being resent in the switch. The switch can avoid the loops whereas the hub cannot avoid the switching loops.
Q17. Explain the role of network topology. (Marked out of 5)
Network is all about the arrangement of the computer networks. It elaborates the workstations as well as nodes in the arranged network. It is also defined as the physical interconnection of the computer network nodes (Bonaventure, 2011). Topologies are easier to maintain and operate in into the central point. Topologies host the layers of the physical interface form the redundancy point of view. With the help of topology the information can be easily transferred with the help of transmission mode. The topologies can transmit the data between the two points of nodes. The topologies can connect directly to the other topologies specially tree topology. The topologies assist the radio transmission lines as well as the fibre optic cables to facilitate the communication between two ending nodes. The topologies can easily offer the simplicity in the operations. The topologies make configuration in order to ease the given services.
Q18. What methods can a cyber-criminal utilize to gain access to a network Describe 3 methods. (Marked out of 5)
There are various ways in which a cyber-criminal or hacker can gain access to a network. The large connectivity of various networks with each other increases the risk of data security breach and makes it exposed to cyber criminals or hackers. Three most common ways in which a cyber criminal may gain access to a network are Phishing, Malware and Cookie theft. Phishing is a technique of sending misleading or fake emails which look genuine. These emails are designed to make the receiver believe they are real and intend to steal confidential information such as passwords and other details. These emails intend to generate an emergency response alluring the reader to respond or click on links provided which leads to exposing the network to the hackers and thus increasing threat of network breach. Another way is through malware which is a malicious software written with the intention of compromising a network and stealing data available on the network. These software are capable of stealing confidential data, tracking network activities and also modifying system settings (Edward amp Bramante, 2009). There can be various types of malware namely virus, trojans, spyware, keylogger and so on. Cookie thefts can occur in the form of browser cache when visiting various websites on the network, malicious cookies may get stored in the system leading to breach. These can store information related to passwords, financial data, credentials etc.
Q19. Which OSI layer is considered the media access control layer (Marked out of 5)
In the OSI layer model the Media Access Control layer or the MAC layer is in a part of layer 2 or the data link layer (Edward ampamp Bramante, 2009). It is responsible for the transfer of data packets from the network interface card to remotely shared channel. It is also an interface between the Logical Link Control Ethernet sub-layer and the physical layer 1. It is a duplex communication channel in a multi-point network. Mac addresses provide unique identities which help in the identification of multiple devices on the data link layer. It is a 12digit hexadecimal number. It must be noted that MAC and IP addresses are two different things. MAC addresses work at level 2 while IP address works at level 3. During data transmission, the MAC block transforms higher frames into compatible frames which can be easily supported by the transmission medium. MAC is also responsible for clearing any kind of congestion by the help of re-transmission in case a jam signal occurs. While the transmission of data from physical layer, MAC ensures data integrity by the verification of the senders frame sequences before transferring the data to the higher levels. This helps in protecting the system from unauthorized access.
Q20. Describe the Bus topology. (Marked out of 5)
A network topology is the pattern in which systems/nodes are connected to each other. The Bus topology is one of the simplest ways to arrange a network cabling and the easiest to implement. In this topology all nodes are connect to a single cable system which is shared by all. To avoid an open loop condition the cable is terminated at each end. The major benefits of this topology are that its very easy to maintain and install. It is easier to add more nodes and requires less cabling compared to other types which makes it cost efficient to implement. The disadvantages of this type are that a cable breakage at any node can cause loss of network access for all other nodes of the arrangement (Edward ampamp Bramante, 2009). Looking at a longer frame of time the maintenance can be little expensive. The speed of data communication is slower than other network topology. Every time a new node is added it affects the entire network system traffic flow and there is also a limit to the total number of nodes that can be added to a particular segment. Collision is also a common error of the bus topology as there is no mechanism to detect collisions within a bus topology. To avoid this often and input output controller may be used in the form of a bus master.
References
Bonaventure, O. (2011). Computer Networking Principles, Protocols and Practice Release 0.25. The Saylor Foundation.Dordal, P. (2014). An Introduction to Computer Networks.Edward, J. ampamp Bramante, R. (2009). Networking Self-Teaching Guide. Indianapolis
Oppenheimer, P. (2011). Analyzing Business Goals and Constraints. Top-Down Network Design (3rd ed., pp. 3-5). Indianapolis, In Cisco Press.
Velte, T. J., amp Velte, A. T. (2014). Cisco a beginners guide . New York, NY McGraw-Hill Education. Pages 123-138.Wiley Publishing, Inc.