Provide short answers to the following six questions. Your answers should be cle

Question

Provide short answers to the following six questions. Your answers should be clear, concise and to the point. Prepare single document (MS Word or PDF) along with title page and submit it online using Turnitin.

Question 1: The address depletion of IPv4 and other shortcomings of this protocol prompted a new version of IP known as IPv6. Explain the advantages of this new IPv6 when compared to IPv4? (3 Marks)

Question 2: Migrating from IPv4 to IPv6 is known as transition from version 4 to version 6 and requires proper strategies to handle this transition. Explain each of the strategies for this migration process using appropriate examples. (4 Marks)

Question 3: In a peer-to-peer (P2P) network, Internet users that are ready to share their resources become peers and form a network. Describe the differences between centralised and decentralised P2P networks? Discuss the advantages and disadvantages of both networks. (3 Marks)

Question 4: What is a Distributed Hash Table (DHT) and how is it used in P2P networks? Briefly explain how a DHT works with an example of a P2P network. (3 Marks)

Question 5: In the client-server paradigm, explain which entity provides the service and which entity receives the service. Why should a server be run all the time, but a client can be run when it is needed? (3 Marks)

Question 6: When an HTTP server receives a request message from an HTTP client, how does the server know when all headers have arrived and the body of the message is to follow? (4 Marks)

Online submission via Turnitin is required for this assignment. Details will be provided by your subject lecturer.

Explanation / Answer

here are the answers of all questions, i am unable to sumit pdf/Ms-word file here, so if you need that only then contact me on sbhabad3@gmail.com else just copy the following text and put it into ms word

1)

IPv6 in addition to offering a significantly larger address space, has many other advantages over IPv4:

The IPv6 protocol has built in support for multicast 1  transmission, while with IPv4 this feature is optional.

IPv6 devices allocate also an only locally accessible and valid IPv6 address for a client connected, which allows communication between endpoints on the same sub-network regardless of the presence of a router. 2

As for security features, the IPsec support (authentication and encryption) is a mandatory component of the IPv6 protocol, while in case of IPv4 this feature is optional.

Contrary to the Mobile IPv4 protocol, the Mobile IPv6 (MIPv6) helps avoid triangular routing experienced earlier, and makes it possible for mobile (WiFi) clients to select a new router without renumbering, which results in a more reliable and faster connection with less network interruption.

In case of IPv4, data packages have an upper size limit of 64 kB (kilobytes), while with IPv6 this may be extended up to 4GB (gigabytes), significantly increasing the transmission rate.

2)

a) Dual Stack Routers

A router can be installed with both IPv4 and IPv6 addresses configured on its interfaces pointing to the network of relevant IP scheme.

server having IPv4 as well as IPv6 address configured for it can now speak with all the hosts on both the IPv4 as well as the IPv6 networks with the help of a Dual Stack Router. The Dual Stack Router, can communicate with both the networks. It provides a medium for the hosts to access a server without changing their respective IP versions.

b) Tunneling

In a scenario where different IP versions exist on intermediate path or transit networks, tunneling provides a better solution where user’s data can pass through a non-supported IP version.

c) NAT Protocol Translation

This is another important method of transition to IPv6 by means of a NAT-PT (Network Address Translation – Protocol Translation) enabled device. With the help of a NAT-PT device, actual can take place happens between IPv4 and IPv6 packets and vice versa.

A host with IPv4 address sends a request to an IPv6 enabled server on Internet that does not understand IPv4 address. In this scenario, the NAT-PT device can help them communicate. When the IPv4 host sends a request packet to the IPv6 server, the NAT-PT device/router strips down the IPv4 packet, removes IPv4 header, and adds IPv6 header and passes it through the Internet. When a response from the IPv6 server comes for the IPv4 host, the router does vice versa.

3)

P2P is never "pure" centralized (represented by a traditional client-server architecture) - if you talk about centralized P2P approaches, it means hybrid systems, where several meta information about the data and peers are stored on multiple "centralized" / well-known server entities. These information sets may include parameters like the file availability, bandwitdth, IP-addresses, latency value, etc. The data transmission (for the payload) is still organized in a decentralized process, directly from peer to peer.

In a pure decentralized approach, the data exchange of these meta information has to be managed without such well-defined server systems. Accordingly, each communication handshake process between the peers incluses an information exchange these meta data. By finishing the handshake process, each peer has knowledge about its "neighborhood".

4) Distributed Hash Table and p2p networks

A distributed hash table (DHT) is a class of a decentralized distributed system that provides a lookup service similar to a hash table: (key, value) pairs are stored in a DHT, and any participating node can efficiently retrieve the value associated with a given key. Responsibility for maintaining the mapping from keys to values is distributed among the nodes, in such a way that a change in the set of participants causes a minimal amount of disruption. This allows a DHT to scale to extremely large numbers of nodes and to handle continual node arrivals, departures, and failures.

DHTs characteristically emphasize the following properties:

Autonomy and decentralization: the nodes collectively form the system without any central coordination.

Fault tolerance: the system should be reliable (in some sense) even with nodes continuously joining, leaving, and failing.

Scalability: the system should function efficiently even with thousands or millions of nodes.

A key technique used to achieve these goals is that any one node needs to coordinate with only a few other nodes in the system – most commonly,O(log n) of the  participants (see below) – so that only a limited amount of work needs to be done for each change in membership.

Some DHT designs seek to be secure against malicious participants[7] and to allow participants to remain anonymous, though this is less common than in many other peer-to-peer (especially file sharing) systems; see anonymous P2P.

Finally, DHTs must deal with more traditional distributed systems issues such as load balancing, data integrity, and performance (in particular, ensuring that operations such as routing and data storage or retrieval complete quickly).

5)

Sometimes, one (computational) entity has something that another (computational) entity needs. For example, a baker may have cookies, and you may be hungry. In this case, the entity that has the thing--the baker--is called a server and the entity that needs the thing--you--is called a client. Although these terms are often used without further explanation, you can see from this description that a client and a server are defined with respect to some (computational) need, or service (like a cookie).

In the computational world, a server is often something that provides a particular service to other computers connected by a network. For example, it is common for an organization to have a lot of disks on which its members' information is stored, and to have a single machine responsible for providing access to this storage space. This machine is called a disk server or a file server. Another machine in the same organization might control the public html access for that organization's world-wide web pages. That machine would be the organization's web server. Yet another machine might be in charge of electronic mail for the organization: the mail server.

In each of these cases, the service is described by what is provided. But it is also important to characterize how the service is provided, in what form, when, by whom, and to whom, whether it is provided once or repeatedly, whether it is provided to one client at a time or to many clients simultaneously, and who is responsible for initiating the transaction. For example, an important message may be transmitted by certified mail, or it may be communicated by announcement over a public address system. These two services may communicate the same information, but they do so in dramatically different ways.

a. A server can provide a variety of services

Some service specializations don't fit neatly under the same abstraction. For example, a letter can be sent certified; a return receipt can be requested. Requesting a return receipt even changes the contract between the client -- the mail sender -- and the postal system so that their interaction pattern is different. In traditional mail transmission, the client gives the item to the post office and the interaction ends. (Of course, the post office is still obliged to carry out its end of the deal, delivery.) When a return receipt is requested, the transaction does not end here. Instead, delivery involves the post office's obtaining a signature from the recipient. This signature needs to be transmitted back to the sender; only then is the original transmission service complete. This amounts to the postal equivalent of a callback. (See the chapter on Intelligent Objects.)

The same server that provides these transmission and delivery services -- the post office -- also provides a number of other services, some of which may not even seem related. For example, the United States Postal Service sells stamps and money orders. By special arrangement (i.e., the rental of a post office box) it will hold your mail for you. Some post offices will even provide you with a passport. This last service is one provided by the post office acting on behalf of the Passport Agency.

6) A host sets the value of the timeout parameter to the time that the host will allows an idle connection to remain open before it is closed. A connection is idle if no data is sent or received by a host.

The max parameter indicates the maximum number of requests that a client will make, or that a server will allow to be made on the persistent connection. Once the specified number of requests and responses have been sent, the host that included the parameter could close the connection.

However, the server is free to close the connection after an arbitrary time or number of requests (just as long as it returns the response to the current request). How this is implemented depends on your HTTP server

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