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DNS is important in resolving the URLs you enter into the address bar of your browser. A lot of work goes into Domain Name Resolution. It is a sort of recursive operation that helps your browser get the IP address of the website you are trying to reach out. If interested, you can read more about DNS Lookup and Servers.

The term DNS Cache refers to the local cache that contains the resolved IP addresses of websites that you frequent. The idea of DNS Cache is to save time that would otherwise be spent on contacting DNS servers that would start a set of recursive operations to find out the actual IP address of the URL you need to reach. But this cache can be poisoned by cybercriminals simply by changing the entries in your DNS cache to fake IP addresses for the websites you use.

What is DNS Hijacking

The most common method for DNS Hijacking is to install malware on your computer that changes the DNS so that whenever your browser tries to resolve a URL, it contacts one of the fake DNS servers instead of real DNS servers that are used by ICANN (authority of Internet that is responsible for registering domains, managing them, providing them with IP addresses, maintaining the contact addresses and more). The direct DNS servers that your computer contacts are the DNS servers being operated by your Internet Service Provider – unless you’ve changed them to something else. When an internet connection is bought, the DNS servers in use are of the ISP – recognized by ICANN.

The malware on your computer changes the default DNS trusted by your computer to point to some other IP address. That way, when your browser tries to resolve an IP address, your computer contacts a fake DNS server that gives you the wrong IP address. This results in your browser loading a malicious website that may compromise your computer or steal your credentials etc.

DNS Hijacking vs. DNS Cache Poisoning

Though both happen at the local level, their origins are from fake DNS servers. While DNS hijacking involves malware, DNS Cache poisoning involves overwriting your local DNS cache with fake values that redirect your browser to malicious websites. DNS Cache Poisoning or Spoofing involves techniques such as the bombardment of fake IP addresses that your computer picks up while the genuine DNS servers are still busy resolving the URL. That is, in the time that takes by genuine DNS servers to resolve a URL, the cybercriminals send plenty of responses that equate the URL with fake IP addresses.

For example, you type chúng tôi in your browser. By the time a genuine DNS server looks up the addresses, your computer receives more than one resolution that the site is at XYZ IP address. This will make your computer believe that the site is at XYZ even though the genuine DNS server sends the genuine IP address because the cybercriminals’ DNS servers sent many responses containing a fake IP for chúng tôi

This difference in time is used effectively by cybercriminals who have many fake DNS servers to get your computer note down wrong and malicious IP addresses to the cache. So one out of the ten fake DNS resolutions sent by cybercriminals’ DNS servers takes precedence over one genuine DNS resolution sent by the genuine DNS servers. Other methods of DNS Cache Poisoning and prevention are listed in the link provided above.

Though DNS Cache Poisoning and DNS Hijacking are used interchangeably, there is a small difference between them. The method of DNS Cache Poisoning does not involve injecting malware into your computer system but is based on different methods like the one explained above where fake DNS servers send a URL resolution faster than the genuine DNS server and thus the cache is poisoned. Once the cache is poisoned, when you use an infected website, your computer is compromised. In the case of DNS Hijacking, you are already infected. A malware changes your default DNS service provider to something that the cybercriminals want. And from there, they control your URL resolutions (DNS lookups), and then they keep on poisoning your DNS cache.

How to prevent DNS Hijacking

We have discussed how to prevent DNS poisoning already. To stop or prevent DNS Hijacking, it is recommended that you use good security software that keeps malware such as DNS changers away. Using a good Firewall. While a hardware-based firewall is best, if you do not have it, you could turn on your router firewall at the least.

If you think you are already infected, it is better to delete the contents of the HOSTS file and reset the Hosts File. After doing this, go ahead and use antimalware that helps you get rid of DNS Changers.

Check if any DNS changer has changed your DNS. If it has, you should change your DNS settings. You can check it automatically. Alternatively, you can check for the DNS manually. Start by checking the DNS mentioned in Router and then in individual computers on your network. I would recommend that you flush your Windows DNS Cache and change your router DNS to some other DNS like Comodo DNS, Open DNS, Google Public DNS, Yandex Secure DNS, Angel DNS, etc. A secure DNS in the router is better than configuring each computer.

There are tools that may interest you: F-Secure Router Checker will check for DNS hijacking, this online tool checks for DNS Hijackings, and WhiteHat Security Tool monitors DNS hijackings.

Now read: What is Domain Hijacking and how to recover a hijacked domain.

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What Is A Replay Attack?

A replay attack is a type of network assault in which an attacker discovers and fraudulently delays or repeats a data transaction. The sender or a hostile actor intercepts the data and retransmits it, causing the data transfer to be delayed or repeated. In other terms, a replay attack is a security protocol attack that uses replays of data transmission from a different sender into the intended receiving system to deceive the participants into believing the data communication was successful. Attackers can use replay assaults to gain access to a network, obtain information that would otherwise be unavailable, or execute a duplicate transaction.

If the replay attack is not mitigated, networks and computers that are subjected to it will see the attack process as valid communications.

Replaying a message sent to a network by an attacker that was previously sent by an authorised user is an example of a replay attack.

Despite the fact that the communications are encrypted and the attacker does not have access to the real keys, retransmission of legitimate data or login messages might assist them in gaining adequate network access.

By replicating an authentication message, a replay attack can get access to resources while also confusing the destination host.

How Does a Replay Attack Work?

Take a look at this real-life assault scenario. By sending an encrypted message to the firm’s financial administrator, a corporate employee requests a money transfer. This communication is intercepted by an attacker, who captures it and may now resend it. The communication is already correctly encrypted and seems valid to the financial administrator since it is an authentic message that has merely been resend.

In this case, unless the financial administrator has cause to be suspicious, he or she is likely to react to the new request. A huge quantity of money might be sent to the attacker’s bank account as a retaliation.

How to Prevent a Replay Attack?

Preventing such an attack is all about using the proper encryption technology. Encrypted communications contain “keys” that, when decoded at the conclusion of the transmission, open the message.

It makes no difference in a replay assault whether the attacker who intercepted the initial transmission can read or interpret the key. All he or she needs to do is capture and transmit the full thing, message and key included.

To mitigate this risk, both the sender and the recipient should generate a fully random session key, which is a sort of code that is only valid for one transaction and cannot be used again.

Using timestamps on all communications is another protective strategy for this sort of attack. It stops hackers from resending communications transmitted more than a particular amount of time ago, so narrowing the window of opportunity for an attacker to listen, syphon off the message, and resent it.

Another way to prevent being a victim is to use a unique password for each transaction, which is only used once and then destroyed. This guarantees that even if an attacker records and resends the communication, the encryption code has expired and is no longer functional.

What Is A Refresh Cycle?

In your computer, there are likely two types of RAM class memory. Only one is referred to as RAM: the system memory or system RAM. This class of RAM is called DRAM. In this class, you may also have some SSDs with integrated DRAM. The VRAM on a graphics card is also a subset of DRAM. You’ll have a different type of RAM on the actual CPU and GPU dies themselves. SRAM is used for on-die caches.

SRAM is speedy. However, it is not particularly dense in terms of gigabytes per square centimeter, which also contributes to its high price. DRAM is slower. However, it has a much higher storage density and is much cheaper. For this reason, SRAM is used in small quantities on processor dies as high-speed memory, and DRAM is used for larger memory pools like the ones described above.

The distinction between SRAM and DRAM is evident in their actual structure. SRAM uses four to six transistors, while DRAM uses a single transistor and a capacitor. This is where the storage density comparison comes in. There are simply fewer parts in DRAM, making each memory cell smaller.

The design differences have another effect, however, one large enough to be the titular naming factor of the two. The S in SRAM stands for Static, while the D in DRAM stands for Dynamic. This represents that SRAM can retain its contents indefinitely, while DRAM needs to be regularly refreshed.

Note: This assumes that a constant power supply is available. SRAM is still volatile memory, and if power is lost, it will lose the data it holds. Just like DRAM.

What Is a Memory Refresh?

The circuit-level architecture of DRAM means that the charge of a memory cell decays over time. Each memory cell must be regularly refreshed to allow DRAM to store data for long periods. There are a couple of essential things to know about this. The first is that the memory can’t be accessed while refreshed. This also means that performance can be limited by how often the DRAM cells need refreshing.

Generally, DRAM cells are refreshed every 64 milliseconds, though this halves at high temperatures. Each row of cells is refreshed independently to prevent this from happening all at once, causing a significant hiccup every 64 milliseconds.

Cleverly the memory controller also times refresh cycles to occur while the RAM module does other things that prevent it from reading or writing memory, such as transmitting read data. Thankfully, the amount of time needed to refresh a cell is small, generally 75 or 120 nanoseconds. This means a DRAM chip spends roughly 0.4% to 5% of its time performing a refresh operation.

How to Refresh DRAM

All this happens automatically. The memory controller manages it all without the CPU being aware of it.

Outliers

DRAM charge does decay, but research has shown that the rate varies wildly between DRAM cells, even on a single chip. The top percent or so may be able to hold their data for up to 50 seconds without needing a refresh at standard temperatures. 90% can store data for 10 seconds, 99% for three seconds, and 99.9% for one second.

Unfortunately, some outliers need to be refreshed much more often. To allow for even the worst-case scenarios, DRAM refresh times are low. This choice does ensure that no data is ever lost, but it also affects power usage and performance.

Some researchers have proposed alternative methods of analyzing and binning the RAM cells and prefer using the ones with better decay times. This would lead to improved power usage, especially useful on low-power battery-powered devices. It would also, however, lead to variable levels of RAM performance.

Additionally, the change in decay time based on temperature would have to be factored in. Even worse, some cells simply lose charge retention performance occasionally, meaning relying on this too much could sometimes result in a presumed good memory cell being bad, requiring regular rebinning.

Conclusion

The refresh cycle is the process in DRAM modules by which the memory cells are refreshed. This is necessary because the circuit design of DRAM results in charge decay. Regularly refreshing memory cells prevents data loss. SRAM doesn’t need to be refreshed as its circuit design does not result in a charge drain.

Note: Refresh cycle may also refer to a user or organization’s regular updating of hardware.

What Is A Conceptual Framework?

A conceptual framework illustrates the expected relationship between your variables. It defines the relevant objectives for your research process and maps out how they come together to draw coherent conclusions.

TipYou should construct your conceptual framework before you begin collecting your data. Conceptual frameworks are often represented in a visual format and illustrate cause-and-effect relationships. You can start conceptualizing this as you determine your relevant paper, thesis, or dissertation topic.

Keep reading for a step-by-step guide to help you construct your own conceptual framework.

Developing a conceptual framework in research

A conceptual framework is a representation of the relationship you expect to see between your variables, or the characteristics or properties that you want to study.

Conceptual frameworks can be written or visual and are generally developed based on a literature review of existing studies about your topic.

Step 1: Choose your research question

Your research question guides your work by determining exactly what you want to find out, giving your research process a clear focus.

Example: Research questionLet’s say you want to study whether students who study more hours get higher exam scores. To investigate this question, you can use methods such as an experiment or a survey to test the relationship between variables.

However, before you start collecting your data, consider constructing a conceptual framework. This will help you map out which variables you will measure and how you expect them to relate to one another.

Step 2: Select your independent and dependent variables

In order to move forward with your research question and test a cause-and-effect relationship, you must first identify at least two key variables: your independent and dependent variables.

Example: VariablesFollowing our example:

The expected cause, “hours of study,” is the independent variable (the predictor, or explanatory variable)

The expected effect, “exam score,” is the dependent variable (the response, or outcome variable).

In other words, you suspect that “exam score” depends on “hours of study.” Thus, your hypothesis will be that the more hours a student studies, the better they will do on the exam.

Note that causal relationships often involve several independent variables that affect the dependent variable. For the purpose of this example, we’ll work with just one independent variable (“hours of study”).

Step 3: Visualize your cause-and-effect relationship

Now that you’ve figured out your research question and variables, the first step in designing your conceptual framework is visualizing your expected cause-and-effect relationship.

We demonstrate this using basic design components of boxes and arrows. Here, each variable appears in a box. To indicate a causal relationship, each arrow should start from the independent variable (the cause) and point to the dependent variable (the effect).

Step 4: Identify other influencing variables

It’s crucial to identify other variables that can influence the relationship between your independent and dependent variables early in your research process.

Some common variables to include are moderating, mediating, and control variables.

Moderating variables

Moderating variable (or moderators) alter the effect that an independent variable has on a dependent variable. In other words, moderators change the “effect” component of the cause-and-effect relationship.

Example: ModeratorWe expect that the number of hours a student studies is related to their exam score—i.e., the more you prepare, the higher your score will be.

Let’s add the moderator “IQ.” Here, a student’s IQ level can change the effect that the variable “hours of study” has on the exam score. The higher the IQ, the fewer hours of study are needed to do well on the exam.

We expect that the “IQ” moderator moderates the effect that the number of study hours has on the exam score.

Let’s take a look at how this might work. The graph below shows how the number of hours spent studying affects exam score. As expected, the more hours you study, the better your results. Here, a student who studies for 20 hours will get a perfect score.

But the graph looks different when we add our “IQ” moderator of 120. A student with this IQ will achieve a perfect score after just 15 hours of study.

Below, the value of the “IQ” moderator has been increased to 150. A student with this IQ will only need to invest five hours of study in order to get a perfect score.

Here, we see that a moderating variable does indeed change the cause-and-effect relationship between two variables.

Mediating variables

Now we’ll expand the framework by adding a mediating variable. Mediating variables link the independent and dependent variables, allowing the relationship between them to be better explained.

Example: MediatorThe mediating variable of “number of practice problems completed” comes between the independent and dependent variables.

Hours of study impacts the number of practice problems, which in turn impacts the exam score.

Here’s how the conceptual framework might look if a mediator variable were involved:

NoteKeep in mind that mediating variables can be difficult to interpret. Take care when drawing conclusions from them.

Moderator vs. mediator

It’s important not to confuse moderating and mediating variables. To remember the difference, you can think of them in relation to the independent variable:

A moderating variable is not affected by the independent variable, even though it affects the dependent variable. For example, no matter how many hours you study (the independent variable), your IQ will not get higher.

A mediating variable is affected by the independent variable. In turn, it also affects the dependent variable. Therefore, it links the two variables and helps explain the relationship between them.

Control variables

Lastly, control variables must also be taken into account. These are variables that are held constant so that they don’t interfere with the results. Even though you aren’t interested in measuring them for your study, it’s crucial to be aware of as many of them as you can be.

Example: Control variableIt is very possible that if a student feels ill, they will get a lower score on the exam. However, we are not interested in measuring health outcomes a part of our research.

This makes “health” a good candidate for a control variable. It still impacts our results, but we aren’t interested in studying it.

Frequently asked questions about conceptual models Cite this Scribbr article

Swaen, B. & George, T. Retrieved July 17, 2023,

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Hdg Explains : What Is A Computer Server?

“The server is down!”

“I can’t log into the server.”

Table of Contents

“The servers are at capacity.”

These are the sorts of phrases we hear on a daily basis when using the internet, but what exactly is a “server”. It’s one of those terms that everyone uses, but few people really know any details about. 

There’s a good chance you found this article by typing “What is a server?” into a search engine. It’s nothing to be ashamed of! It’s an essential piece of knowledge any internet user should know and you’re about to get all the essential info right here.

What the Internet ACTUALLY Is

The concept is actually pretty simple. The internet is simply a collection of computers connected together by communications hardware, such as routers and network cables.

Whenever you access a web page, watch a video or send an email, there’s another computer somewhere in the world that’s providing the content or acting as the go-between to help you communicate with someone else.

What Is a Server vs a Client

These computers, the ones providing the SERVices, are what we generally refer to as “servers”. The computers that receive those services are called “clients”. See? It’s a pretty simple concept. Servers serve content and services to clients. However, that doesn’t tell us much about the servers themselves. Just what are they exactly?

Servers are Just Computers

Any computer can be a server. Your home computer can be a server. Although your internet service provider probably prohibits the practice on home internet subscriptions. It’s not just traditional desktop computers either. Any network-connected computer can act as a server, client or both. 

Rather than being a description of a specific device, the concepts of “client” and “server” describe roles that computers have on a network. For example, if you have an IP security camera, those have server software installed on its tiny embedded computer. When you access the camera, you’re logging into a server that provides you with a video stream.

 That being said, not every computer is suitable to act as a server. So often when the word “server” is used, it refers to specialized computers that are built from the ground up to act specifically as servers. 

Server Hardware is Special

If you were to venture into the typical server room of a website hosting company, you’d see rows and rows of cabinets. Inside these cabinets, you’d see racks of servers stacked on top of each other. As seen in this picture.

Inside each of these racks, you’ll find a special server-grade motherboard, RAM, CPU and storage. In principle, these are the same components as the ones in your computer. Except, inside servers they’re far more powerful, reliable and energy efficient. After all, these computers are working 24/7, serving millions of requests from clients every day.

This is why server hardware is much more expensive than the stuff you find in a consumer PC. Every minute a server is down may cause thousands of dollars in losses. So it’s worth paying a premium to ensure that the internet services in question remain available.

We won’t go into deep details here, but server hardware stands out in the following main ways:

Server motherboards support large amounts of RAM. Terabytes worth in many cases!

Server motherboards often have multiple CPU sockets

Server CPUs tend to have many CPU cores and large amounts of cache

Server RAM is usually of a special error-correcting type to ensure stability

Server power supplies may be redundant, instantly switching over to a backup if the main unit fails

Rack servers also don’t have keyboards, mice, screens or speakers. Instead, they are accessed via the network through the command line or by using a remote desktop application. Although they usually do have the required ports to hook up these peripherals if needed.

Local Servers

A “local” server is one that runs on your local home network, rather than somewhere “out there” on the internet. 

There’s a good chance that you have some sort of server application running on one of your home computers and don’t even know it. The aforementioned IP camera embedded software is one example, but there are other applications that run on regular desktop and laptop systems that also fit the bill. 

For example, the popular Plex application runs a media server on your local machine. This is like Netflix running on your local network. Calibre acts as a local file server for ebooks and, of course, network-attached storage devices are also a sort of local network server. So, as you can see, servers are everywhere. Even in your home!

Common Server Types

While all servers have the same general job, there are clear subtypes of servers that specialize in different tasks.

Web servers are incredibly common. The website you are reading at this very moment was sent to you by a web server. Your web browser acts as the client and requests website data from the server. It then receives the HTML (Hypertext Markup Language) web page code and renders it to your screen. From there it enters your eyeballs and this information is now in your head. Neat, right?

File servers use the FTP or File Transfer Protocol standard rather than HTML and exist to move files from their own hard drives to yours.

Email servers handle the sending and receiving of email messages. Basically it’s an electronic post office.

The list goes on. There are servers that verify login details, servers that act as a proxy between company computers and the internet, media streaming servers at companies like Netflix and more. As more internet services are invented, we can expect new types of specialized server hardware and software to come along as time goes by.

“Mainframe” vs “Server”

One final point of confusion is the difference between a “mainframe” computer and a server. While a server is essentially a beefed-up desktop computer, mainframes are an entirely different beast.

These computers are much, much more powerful than server hardware. The emphasis on reliability and spare processing capacity is much higher and these computers are usually used for jobs that are mission critical.

Online banking is one example where mainframes may be a better choice. Especially since mainframe computers are built to zip through as many “transactions” as possible. These computers are usually about the size of a large fridge. Often, they’re as big as ten rack-mounted servers.

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What Is Cloud Business Intelligence? A Full Synopsis

Take a look at the comprehensive definition and synopsis of “Cloud Business Intelligence”

In this data-driven decade, businesses are well aware that they must innovate to capitalize on the data’s value and outperform the competition.

Because of this, a significant shift from storing data in on-premises databases to the cloud has occurred. In today’s cloud-first world, bringing traditional business intelligence solutions from the on-premises era is a recipe for disaster.

As a result, companies that are considered to be leaders in analytics have not only adopted the cloud as a platform for storing their data, but they have also brought the most important data applications with them. One of these important uses is: business intelligence in the cloud Modern cloud business intelligence is a way to directly query cloud data platforms like Snowflake, Databricks, Google BigQuery, Microsoft Azure, and AWS Redshift. Cloud business intelligence is a type of business intelligence. These solutions can benefit from the scale, speed, and interactivity that cloud ecosystems can only provide.

What is Business Intelligence (BI) in the Cloud?

Cloud business knowledge (BI) is the most common way of interfacing with cloud information, sorting out this information into an information model, and dissecting this information to extricate experiences to preferably illuminate navigation. The best cloud business intelligence tools go one step further by letting users use insights to automatically drive actions in addition to just finding insights.

Customer data, sales data, financial data, operational data, and other data from a variety of sources must frequently be combined into a single, organized cloud platform, such as a data lakehouse or cloud data warehouse. If you want business users to be able to use data to understand and respond to customer behavior, identify trends, steer clear of unnecessary risk, and plan for the future, this is a necessity.

Expanded Information Permeability:

In the past, siloed data, in which information from various systems remains isolated, has been a problem for businesses. These barriers are broken down when data is moved to the cloud, giving a much more complete picture of the business. Organizations can investigate this data in its entirety thanks to effective cloud BI solutions’ direct integration with cloud data platforms. Businesses can get a true 360-degree view of their operations thanks to this increased visibility.

Enhanced Cooperation:

Collaboration is more important than ever for success in today’s market, which is dominated by hybrid, remote, and global teams. By sharing data insights in real time, teams can collaborate more effectively with cloud BI. The fact that all team members have access to the same data set makes it easier to spot opportunities and allows for more precise analysis.

Increased Speed from Insight to Action:

Time is money, and businesses that wait for insights to make decisions are sacrificing value. That all changes with cloud BI solutions, especially when they are part of a strategy for self-service BI. They can quickly ask and answer their questions and, more importantly, act on these insights rather than waiting for a new dashboard to be built.

Reduced Expenses:

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