Assignment # 3 Submitted ToSir AbdulRehmanSubmitted BySohaibAhmadRoll No17271519-052ClassBSCS-BCourseICT   CS-162Semester1st DEPARTMENT OF COMPUTER SCIENCEUNIVERSITY OF GUJRAT Q1. Write acomprehensive note on the types of Network Topologies? Which one is the best inyour opinion and why? Types of network topologies are given below with littleexplanation. BUS TOPOLOGYBus topologyuse a common backbone to connect all devices. It is a network type in e=whichcomputer and network device is connected to a single cable. It transmit dataonly in one direction. Its advantage is that it is used in small networks andeasy to understand.

One disadvantage is that if cables fails then whole networkfails and also cables have limited length. RING TOPOLOGYIn a ringnetwork, every device has exactly two neighbors for communication purposes.All messages travel through aring in the same direction. Disadvantage is failure in any cable or devicebreaks the loop and can take down the entire network. Advantage is transmitting network is not affectedby high traffic or by adding more nodes, as only the nodes having tokens cantransmit data. STAR TOPOLOGYIn star topologyall the computers are connected to a single hub through a cable. This hub isthe central node and all others nodes are connected to the central node.Advantage is every node has itsown dedicated connection to the hub and hub acts as a repeater for data flow.

Hub can be upgraded easily but it is expensive to use and cost of installationis high. TREE TOPOLOGYIt has aroot node and all other nodes are connected to it forming a hierarchy. It isalso called hierarchical topology. It should at least have three levels to thehierarchy. In its simplest form, only hub devices connect directly to the treebus, and each hub functions as the root of a tree of devices. It is used inwide area network. Ifmore nodes are added then maintenance is difficult.

If central hub fails thenwhole network fails. MESH TOPOLOGYMeshtopology introduces the concept of routes. Unlike each of the previoustopologies, messages sent on a mesh network can take any of several possiblepaths from source to destination.

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A mesh network in which every device connects to every otheris called a full mesh. Thereare two techniques to transmit data over the Mesh topology, one is routing andother is  flooding. Advantage is eachconnection can carry its own data load. It provides security and privacy.Its disadvantage is that its installationand configuration is difficult and cabling cost is more, also bulk wiring isrequired. MY OPINIONAll these topologies have some advantages as well asdisadvantages. Best is that which suits you, which gives you friendlyenvironment to operate systems. All are best according to your need.

Meshtopology seems to be best because if any system stops working, it will not failthe whole system but as I have already mentioned that it is costly anddifficult to handle. Q.2Differentiate between Guided and Un-Guided Media? Discuss main types ofun-guided media? Give examples. Guided Media       I.           Guided media requires a physical path fortransmission.      II.           It is called wired communication or boundedtransmission media.    III.

           It provides direction to signal for travelling.    IV.           Its three types are: Ø  Twistedpair cable, coaxial cable and fiber optic cable. Unguided Media       I.           Unguided media is broadcasted through air or sometimesthrough water.      II.           It is called wireless communication or unboundedtransmission media.

    III.           It does not provide any direction for travelling.    IV.

           Its main types are:Ø  Radio wave,microwave and infrared. Types of Unguided MediaThe unguided media is categorized into following types.Radio WavesThe radio waves are generated easily, they are low-frequencysignals and can travel a long distance. The radio waves can penetrate through thebuildings.Micro WavesThe microwaves are transmitted in a straight line and hencerequire the line-of-sight transmission.

The distance covered by the microwavesignal depend on the height of the two antenna. More the taller are antennaslonger is the distance covered by the signal. The microwave has a frequencyhigher than the radio waves. Microwave are used for telephone communicationmobile phones, television distribution, etc.  InfraredWavesInfrared waves are used for shortrange communication. Like, the remote control for televisions, VCRs, etc.

usesinfrared waves. It cannot penetrate through obstacles. The government licenseis not required, to operate an infrared system as it is more secure againsteavesdropping. Q3. Discussgenerally the main security concerns to your computer while working in thecyber world? Also, state some protective measures to safeguard your computer?MALWAREMalware is an abbreviated term meaning “malicious software.”This is software that is specifically designed to gain access or damage acomputer without the knowledge of the owner. There are various types of malwareincluding spyware, keyloggers, true viruses, worms, or any type of maliciouscode that infiltrates a computer.

 BOTNETThe botnet is an example of using good technologies for badintentions. A botnet is nothing more than a string of connected computerscoordinated together to perform a task. That can be maintaining a chat room, orit can be taking control of your computer. Botnets are just one of the manyperils out there on the Internet. SPOOFINGAn attack in which someone intercepts and co-opts an active,established session. IP spoofing is also an attack method by which IP packetsare sent with a false source address, which may try to circumvent firewalls byadopting the IP address of a trusted source. This fools the firewall intothinking that the packets from the hacker are actually from a trusted source.IP spoofing can also be used simply to hide the true origin of an attack.

 TROJANHORSETrojan Horse hides malware in what appears to be a normalfile. There are a wide variety of Trojan viruses on the Internet landscape thatcan perform an array of tasks. Most Trojans are typically aimed at takingcontrol of a user’s computer, stealing data and inserting more malware on to avictim’s computer.

 Protectionagainst malwareThe best protection from malware continues to be the usual advice is tobe careful about what email attachments you open, be cautious when surfing andstay away from suspicious websites, and install and maintain an updated,quality antivirus program. Protectionagainst botnetUse a firewall when browsing the Internet. This is easy to do with Maccomputers as they come with Firewall software pre-installed. If you’re using a Windows-basedmachine, you might need to install third-party software. Don’t visit websitesthat are known distributors of malware. One of the things that a full-serviceInternet security suite can do is warn you when you’re visiting such sites. Protectionagainst spoofingDon’t visit unsafe websites.

Most Internetsecurity suites include a component alerting you that the site you’re about tovisit is unsafe. Don’t download attachments or click on links in unfamiliaremails. Protect accounts with complex, unique passwords.