1- Describe how secret key and public key cryptosystems work. 2- Distinguish bet
ID: 3575701 • Letter: 1
Question
1- Describe how secret key and public key cryptosystems work.
2- Distinguish between physical and logical address.
3- Distinguish between flat memory model and segmented memory model
4- Describe the process of translating a logical segment address into a physical address.
5- Describe the process of translating a virtual address (in pagination) into physical address.
6- What is an IP address?
7- Explain how the DNS maps a domain name to an IP address
8- What is a protocol? Identify at least three application protocols
9- Describe the process of loading a web page
10- Explain what is the difference between a client and a server
Explanation / Answer
1.The asymmetric key algorithms are the distinguishing technique that is being used in public key cryptography .The key used here by one party to perform encryption is dissimilar to the key used by another in decryption. Each of the users have a pair of cryptographic keys which is a public encryption key and a private decryption key.
2.Logical address is defined as the one which is generated by the CPU. But an address that is seen by the memory unit is called phyical address. It is the one loaded into the memory-address register of the memory.
3.Flat memory model: It is not suitable for general computing or multitasking operating systems. unless enhanced with additional memory management hardware/software; but this is almost always the case in modern CISC processors, which implement advanced memory management and protection technology over a flat memory model.
A flat memory model is generally easier for people to understand, because it is possible to construct a simple mapping between addresses and numbers. This makes it possible to mentally model the address space as a large array and addresses as indices into that array. In a segmented memory model, this mental image of the address space only works within a segment, but not between segments. So far, I have not found a mental model that can accurately describe a segmented memory model.
Segmented memory model: Implemented in original Intel 8086, 8088, 80186, 80286 and supported by 80386 and all subsequent x86 machines through to present day Pentium and Core 2 processors. This memory model has remained ever since in the x86 machines, which now provide multi-mode operation and rarely operate in the compatible segmented mode anyway.It is far superior in preventing buffer overflows. The size of a segment is not fixed, but can be determined at runtime, so it is possible to allocate your buffers in dedicated segments that are sized exactly right for the buffer contained therein. Any attempt to go outside the buffer would immediately result in an error, because you are forming an illegal address. This is not possible with a flat memory model, because you might be addressing an unrelated variable that happens to be located adjacent to the buffer.
6.IP address or also called te Internet Protocol address , is designed to allow one computer or any sort of digital device to communicate with another via the Internet.It allows the location of literally billions of digital devices that are connected to the Internet to be pinpointed and differentiated from other devices.
7.DNS servers answer questions from both inside and outside their own domains. When a server receives a request from outside the domain for information about a name or address inside the domain, it provides the authoritative answer. When a server receives a request from inside its own domain for information about a name or address outside that domain, it passes the request out to another server, usually one managed by its internet service provider.
8.Protocol is the one that uses a set of rules to send and receive messages at the Internet address level.The applications are Real-Time Particle Monitors ,wireless microsensor network.
9. The steps to load a web page is as follows:
10.A server is the one that connects point for several clients who will handle their requests whereas a client is software that connects to the server to perform actions.
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