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Computer Networking
Computer networks are collections of computers which are connected together in order to communicate and transfer information. Questions about computer networks, networking protocols, and how to set them up belong here.
18,810 Questions
A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. WLAN utilizes spread-spectrum or OFDM modulation technology based on radio waves to enable communication between devices in a limited area, also known as the basic service set. This gives users the mobility to move around within a broad coverage area and still be connected to the network. For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops. Public businesses such as coffee shops or malls have begun to offer wireless access to their customers; some are even provided as a free service. Large wireless network projects are being put up in many major cities. Google is even providing a free service to Mountain View, California and has entered a bid to do the same for San Francisco. New York City has also begun a pilot program to cover all five boroughs of the city with wireless Internet access. A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. WLAN utilizes spread-spectrum or OFDM modulation technology based on radio waves to enable communication between devices in a limited area, also known as the basic service set. This gives users the mobility to move around within a broad coverage area and still be connected to the network. For the home user, wireless has become popular due to ease of installation, and location freedom with the gaining popularity of laptops. Public businesses such as coffee shops or malls have begun to offer wireless access to their customers; some are even provided as a free service. Large wireless network projects are being put up in many major cities. Google is even providing a free service to Mountain View, California and has entered a bid to do the same for San Francisco. New York City has also begun a pilot program to cover all five boroughs of the city with wireless Internet access.
What are the advantages and disadvantages of C language?
Advantages of C language
- Speed of the resulting application. C source code can be optimized much more than higher level languages because the language set is relatively small and very efficient.
- That leads to a second advantage that C has which is its application in Firmware programming (hardware). That is due to its ability to use/work with assembly and communicate directly with controllers, processors and other devices.
- C Programming language is very easier to learn. The main advantages of C language is that there is not much vocabulary to learn, and that the programmer can arrange for the program is very fast.
Disadvantages of C Language
- C does not have OOPS feature that's why C++ is developed. If you know any other modern programming language then you already know its disadvantages.
- There is no runtime checking in C language.
- There is no strict type checking (for example: we can pass an integer value for the floating data type).
- C doesn't have the concept of namespace.
- C doesn't have the concept of constructors and destructors.
How cold boot different a warm boot?
A cold boot always begins with the power off whereas a warm boot does not interrupt the power supply. Although there may not appear to be any difference on the surface (a POST is performed regardless), a cold boot is more reliable as it ensures all hardware is properly reset.
When diagnosing hardware issues, it's always best to cold boot the system to ensure consistency. It's also best to let the system rest for at least 30 seconds to allow any residual current to drain before powering up again. Ideally, external peripherals (USB drives, printers, domestic routers, etc) should be turned off as well. Hardware issues are problematic enough without increasing the number of variables you have to contend with.
What are the classifications of computer networks?
The different types of network are Personal Area Network(PAN), Local Area Network (LAN), Campus Area Network(CAN), Metropolitan Area Network (MAN), Wide Area Network (WAN), and Global Area Network (GAN).
by Rhaine
What is the different between segmentation and multiplexing?
MODULATION:
Usually, the signal that we want to transmit, say a speech signal with 4000 Hz frequency, will require a very big antenna. For any signal the frequency f is related to wavelength Las
c = L * f ………………………… (i)
Where c is velocity of light. And antenna length is generally taken as L/2 which simply means for our case antenna length is 75000 m, obviously this size of antenna is too big to use on day to day basis. That is why we take our speech signal or the desired signal and take another high frequency signal known as carrier (carrier can be any signal but should have high frequency and in practice we use a simple continuous wave signal), now we alter one or more parameters of this career signal in accordance with our desired signal, this parameters can be any one or combination of parameters. The basic parameters are amplitude, frequency, and phase of the signal. The result of this alteration we get is known as modulated signal, the desired signal which we wanted to transmit is known as modulating signal also known as base band signal and modulated signal is also known as band pass signal. The whole process is known as MODULATION.
There are many types of modulation starting from amplitude modulation popularly known as AM, frequency modulation (FM), QPSK, PCM, GMSK, QAM etc.
MULTIPLEXING:
Basically there are two types of system, time domain and frequency domain. In time domain we transmit frames, and in frequency domain we transmit in accordance with frequency. Now if there is more than one source of signal and we want to transmit them together then we implement multiplexing. In multiplexing we mix the source signals (off course with some precautions) say if we want to mix them in time domain then our frame will contain some packets form source A and some packets from source B and so on depending upon the constraints of the channel and time frame. The signals that source are generating can either be modulated signals or we can even send our multiplexed signal to the modulator and then modulate the signal. At the receiving end be demultiplex the signals. In multiplexing we do not provide a dedicated resource to a single source. I.e. we do not dedicate the complete time frame to a single source (in our case it is time frame). Multiplexing is also seen as you are travelling on a four lane road and suddenly it get narrower and turned to single lane, at this point the traffic police will allow one car from each lane to drive through that narrow single lane, this is what we called MULTIPLEXING.
MULTIPLE ACCESS:
As the name suggest, multiple access means multiple users can access the channel or link. Multiple access provides dedicated resources to the user (with a time constraint) in comparison to the multiplexing which does not provide any type of resources. There are many type of Multiple access schemes like FDMA frequency division multiple access, TDMA time division multiple access, CDMA code division multiple access, SDMA space division multiple access etc. take the example of FDMA, the whole frequency band is divided into small frequency bands called channels, now each channel is having certain capacity to take the traffic say a channel can accommodate single user at time, then the whole frequency bandwidth can be access by as many users as there are channels, mathematically if we are having a bandwidth of 200 KHz and channel bandwidth is 50 KHz then it means we can accommodate 4 users at a time by giving 50 KHz channel to each. This is so called multiple access, i.e. multiple users can access the bandwidth simultaneously and we do not require any additional hardware at the receiving end to separate the desired user from the other users as we do in Multiplexing. In reality the concept of Multiple Access is more complicated and In GSM each channel can accommodate 8 users at a time and each channel has 200 KHz bandwidth.
Even I am searching its answer. But, I feel, multiplexing is technique and multiple access is way to use this technique.
but there is a difference between multiple access and multiplexing that should be noted:
Multiple access refers to the remote sharing of a communication channel such as a satellite or radio channel by users in highly dispersed loctions. on the other hand, multiplexing refers to the sharing of a channel such as a telephone channel by users confined to a local site.
Modern telephone networks allow bandwidths in their channels that are much larger than those is needed for a digitalized telephone channel. Basically, a number of channels share a common transmission medium with the aim of reducing costs and complexity in the network. Multiplexing is defined as the process by which several signals from different channels share a channel with greater capacity. When the sharing is carried out with respect to a remote resource, such as a satellite, this is referred to as multiple access rather than multiplexing.
According to the definition described in Encyclopedia of Britinica : Multiplexing is defined as the sharing of a communications channel through local combining at a common point. In many cases, however, the communications channel must be efficiently shared among many users that are geographically distributed and that sporadically attempt to communicate at random points in time. Three schemes have been devised for efficient sharing of a single channel.
What is the difference between dijkstra and kruskal's algorithm?
Both of these functions solve the single source shortest path problem. The primary difference in the function of the two algorithms is that Dijkstra's algorithm cannont handle negative edge weights. Bellman-Ford's algorithm can handle some edges with negative weight. It must be remembered, however, that if there is a negative cycle there is no shortest path.
Which port should you connect a router to a lan?
It shouldn't matter which port you use unless it involves a network switch.
What is the difference between RMI and RPC?
RMI simply offers remote access to an object running in another process. But EJB offers far more services than RMI. EJB leverages this remote-object feature of RMI, but also provides other services such as persistence, transaction management, security, and resource management. The EJB server provides all of these complex services which allows EJB developers to worry about business logic instead. For a complete understanding of EJB i suggest Http://edocs.bea.com/wle/rmi/sampejb.htm
What is the difference between a modem and multiplexer?
A decoder takes n inputs and produces 2^n outputs. An encoder takes 2^n inputs and produces n outputs.
A multiplexer selects one line from many lines. The inverse of selection is distribution. A demux essentially transmits data from one line line to 2^n possible output lines. The output line is determined by n select lines. In short, a multiplexer selects an input line, a demultiplexer selects an output line.
The differences between these two circuits is subtle, as far as I can tell. A demux simply selects an output line, nothing more. It's a glorified switch. A decoder takes n inputs, and uses those inputs to determine which of the 2^n output lines is high. This is the difference, I think. A decoder is designed to simply keep one line high. A demux is designed to set one output equal to the input (whether it be high, low, or a changing signal).
What is the difference between database and relational database?
A database is something that stores data. Using tools called Database Management Systems(like Oracle, Informix, Sybase, DB2), you can create, view, modify, and delete databases. Databases can be -Relational -Object Oriented -Object Relational Relational database stores data in tables(called realtions). These tables are related to each other.Just like in our family, our relations are related with each other. In Object Oriented Databases, the information is stored in the form of Objects as in Object Oriented Programming.OODBMS makes database objects appear as programming language objects in one or more porgramming languages. Object relational databases combine the features of both Object Oriented as well as Relational databases. Here you can not only store simple data like text in relational, but you can also store complex objects like images, audio and video in tables.
MD5 (like SHA-1 or CRC32) is a common message-digest algorithm for data integrity. MD5 is widely used as a cryptographic hash function producing a 128-bit (16-byte) hash value or checksum, typically expressed in text format as a 32 digit hexadecimal number (e.g. 90506d869e65e896d5a8474b00097610).
This essentially is a way to digitally sign a block of text or media to prevent tampering or modification. A receiver can calculate the md5 hash value independently to verify the contents match the expected hash value. If a different hash value is computed then the content has been changed from the original.
The newer SHA-1, SHA-256, and SHA-512 algorithms respectively generate a 160-bit, 256-bit, and 512-bit hash value for greater security.
Difference between connectionless and connection oriented communication?
Different from a connectionless protocol, a connection-oriented protocol guaranties the delivery of the information. An example of connection-oriented protocol is (TCP) and a connectionless protocol is (UDP). page/926 A+
What is the digital to digital signal encoding technique?
The digital encoding techniques are of two types--Polar and Bipolar. The polar encoding are--RZ(Return to Zero), NRZ (No RZ) , Manchester and Differential Manchester. Bipolar encoding are--AMI ( Alternate Mark Inversion) and BnZS ( Bipolar n Zero Substitution).
Yes. there is. a man named Jerimah Hacker made his own trail in the 1800's. he wrote it=down on a map for all to use.=
What are Characteristics of a coaxial cable?
Optical-fiber systems have many advantages over metallic-based communication systems. These advantages include interference, attenuation, and bandwidth characteristics. Furthermore, the relatively smaller cross section of fiber-optic cables allows room for substantial growth of the capacity in existing conduits. Fiber-optic characteristics can be classified as linear and nonlinear. Nonlinear characteristics are influenced by parameters, such as bit rates, channel spacing, and power levels.
What are guided unguided media?
guided media is the transmission medium in which data/signal is guided by the cable or wire so used to a specific path. there are 4 types of guided media
--> open wire
-->twisted pair
--> co-axial cable
-->optical fibre
for more details open the link -----
http://www.techbooksforfree.com/intro_to_data_com/page37.html#37
What is the difference between signal and event?
The main different between a traditional signal and a message is their recipient. A signal is often sent to a mass of people, while a message is more individualized.
Architecture of expert expert system?
expert system architecture need to act like the process expert attempt to do for reasoning based on the given facts. architecture comprise of interface, explanation system, inference engine and knowledge editor as a shell,which can be configured on different knowledge area without changing the whole structure of expert system, and the removable part constitute of domain-specific and general knowledge section. in general knowledge section refer to those knowledge representation(usually in the form of ruled-based) symbols which is needed for expert system to running. domain-specific refer to those facts that entered by user or is the conclusion of the last operation in inference part. resemble it to individual experts, general knowledge section have a role of long-terms memory and domain specific have role of working memory which is manipulated or updated by inference engine. in fact inference engine use both of this storage for reasoning and making inference about the problem. generally inference engines use recognize-act chain in order to solve the problem. process of problem solving in forward chaining method for inference start with typing of problem from GUI by user, the facts go into domain specific storage,in this part the first action on recognition-action cycle of inference engine take place. all of the facts in domain-specific storage being compared with rules in general knowledge storage. this part is called matching, after that inference engine need choose the most appropriate one from conflict set(set of rules in matched in first step). for this purpose it may use conflict resolution strategy which is the job of interpreter. interpreter is part of the inference engine that execute selected agenda based on the given criteria. what will happen then is selection of rule based on namely three main category of strategy:1-in the case of two or more condition use the one that are more specific 2-if two or more rule have appropriate condition for selection use the one used in facts 3-if system match the same condition for two different role the latest rule need to be eliminated because iteration may take place. after selection of rule execution part start if executed result is the one desired problem is solved if not, result store in domain-specific section and cycle renewed. the process of inference engine is the same for back-ward and forward chaining what make difference is the load and reload of working memory and other things.(and this is the thing that u need to find out!). explanation system which is part of the shell(you can see more about shell by searching on wikianswer ;)). explanation system provide description about why expert system decide on particular course of action and how it conclude to this result. mechanism counterintutivelly simple. explanation system just exploit the knowledge pattern it followed during the work of inference engine. it track back use storage to find out what have been decided and how inference engine imply based on th rules.(just like it's human counter part) i don't know much about the detailed flow of work in explanation systems but i really love to. knowledge editor as its name imply manipulate the general knowledge storage, adding , deleting and changing undertake by knowledge engineer but knowledge editor written by professional programmer. hope this would help but again check other places because there s lot more u need to know.good luck have fun!
According to computer networking: a top-down approach, the transmission rate of Ethernet LAN is 10 Mbps, 100 Mbps, 1 Gbps and 10 Gbps. Maximum rate can be transmitted to a destination that is not being transmitted to by other users.
What are the disadvantages of using mail merge?
Advantages:
It is quick and easy.
It saves time.
You can address a large number of letters without having to do it yourself as mail merge inserts it for you.
Disadvantages:
It can be used as a scam.
It runs slowly or doesn't run at all when more than one software is running.
If it is email merge all recipients will be able to view all data and information.
What is the C program for byte stuffing?
#include
#include
main()
{
char a[20],fs[50]="",t[6],r[5];
int i,j,p=0,q=0;
clrscr();
printf("enter bit string : ");
scanf("%s",a);
strcat(fs,"01111110");
if(strlen(a)<5)
{
strcat(fs,a);
}
else
{
for(i=0;i
{
for(j=i;j
{
t[p++]=a[j];
}
t[p]='\0';
if(strcmp(t,"11111")==0)
{
strcat(fs,"111110");
i=j-1;
}
else
{
r[0]=a[i];
r[1]='\0';
strcat(fs,r);
}
p=0;
}
for(q=i;q
{
t[p++]=a[q];
}
t[p]='\0';
strcat(fs,t);
}
strcat(fs,"01111110");
printf("After stuffing : %s",fs);
getch();
}
Electronic signals are converted into what when transmitted through fiber optic cables?
depends on the purpose of the device
What are the Example of shareware and freeware?
Microsoft internet explorer is an example for freeware s/w and PDF to DWG Freeware is nice.
Mapped network drive. In Windows networks, an external resource has the form "\\MyServer\MyFolder\MySubFolder\MyFile.doc". The folder part, "\\MyServer\MyFolder\MySubFolder", can be assigned ("mapped") to a drive letter, for example, "M:"; in that case, you refer to the document as "M:\MyFile.doc".
Mapped network drive. In Windows networks, an external resource has the form "\\MyServer\MyFolder\MySubFolder\MyFile.doc". The folder part, "\\MyServer\MyFolder\MySubFolder", can be assigned ("mapped") to a drive letter, for example, "M:"; in that case, you refer to the document as "M:\MyFile.doc".
Mapped network drive. In Windows networks, an external resource has the form "\\MyServer\MyFolder\MySubFolder\MyFile.doc". The folder part, "\\MyServer\MyFolder\MySubFolder", can be assigned ("mapped") to a drive letter, for example, "M:"; in that case, you refer to the document as "M:\MyFile.doc".
Mapped network drive. In Windows networks, an external resource has the form "\\MyServer\MyFolder\MySubFolder\MyFile.doc". The folder part, "\\MyServer\MyFolder\MySubFolder", can be assigned ("mapped") to a drive letter, for example, "M:"; in that case, you refer to the document as "M:\MyFile.doc".
