Sunday, November 13, 2016
Thursday, April 28, 2016
What is a Mail Server?
The Process of Sending an Email
With the click of a mouse button, you can send an email from one point of the globe to another in a matter of seconds. Most of us take this process for granted, giving little thought to how it actually works. It's easy to understand how standard snail-mail gets from point A to point B - but how does an email message make its way from a sender to a recipient? The answer to that question revolves around something called a mail server. You can learn more about the role that mail serves play in email delivery by reading on below.What is a Mail Server?
A mail server is the computerized equivalent of your friendly neighborhood mailman. Every email that is sent passes through a series of mail servers along its way to its intended recipient. Although it may seem like a message is sent instantly - zipping from one PC to another in the blink of an eye - the reality is that a complex series of transfers takes place. Without this series of mail servers, you would only be able to send emails to people whose email address domains matched your own - i.e., you could only send messages from one example.com account to another example.com account.
Types of Mail Servers
Mail servers can be broken down into two main categories: outgoing mail servers and incoming mail servers. Outgoing mail servers are known as SMTP, or Simple Mail Transfer Protocol, servers. Incoming mail servers come in two main varieties. POP3, or Post Office Protocol, version 3, servers are best known for storing sent and received messages on PCs' local hard drives. IMAP, or Internet Message Access Protocol, servers always store copies of messages on servers. Most POP3 servers can store messages on servers, too, which is a lot more convenient.
The Process of Sending an Email
Now that you know the basics about incoming and outgoing mail servers, it will be easier to understand the role that they play in the emailing process. The basic steps of this process are outlined below for your convenience.
Step #1: After composing a message and hitting send, your email client - whether it's Outlook Express or Gmail - connects to your domain's SMTP server. This server can be named many things; a standard example would be smtp.example.com.
Step #2: Your email client communicates with the SMTP server, giving it your email address, the recipient's email address, the message body and any attachments.
Step #3: The SMTP server processes the recipient's email address - especially its domain. If the domain name is the same as the sender's, the message is routed directly over to the domain's POP3 or IMAP server - no routing between servers is needed. If the domain is different, though, the SMTP server will have to communicate with the other domain's server.
Step #4: In order to find the recipient's server, the sender's SMTP server has to communicate with the DNS, or Domain Name Server. The DNS takes the recipient's email domain name and translates it into an IP address. The sender's SMTP server cannot route an email properly with a domain name alone; an IP address is a unique number that is assigned to every computer that is connected to the Internet. By knowing this information, an outgoing mail server can perform its work more efficiently.
Step #5: Now that the SMTP server has the recipient's IP address, it can connect to its SMTP server. This isn't usually done directly, though; instead, the message is routed along a series of unrelated SMTP servers until it arrives at its destination.
Step #6: The recipient's SMTP server scans the incoming message. If it recognizes the domain and the user name, it forwards the message along to the domain's POP3 or IMAP server. From there, it is placed in a sendmail queue until the recipient's email client allows it to be downloaded. At that point, the message can be read by the recipient.
How Email Clients are Handled
Many people use web-based email clients, like Yahoo Mail and Gmail. Those who require a lot more space - especially businesses - often have to invest in their own servers. That means that they also have to have a way of receiving and transmitting emails, which means that they need to set up their own mail servers. To that end, programs like Postfix and Microsoft Exchange are two of the most popular options. Such programs facilitate the preceding process behind the scenes. Those who send and receive messages across those mail servers, of course, generally only see the "send" and "receive" parts of the process.
At the end of the day, a mail server is a computer that helps move files along to their intended destinations. In this case, of course, those files are email messages. As easy as they are to take for granted, it's smart to have a basic grasp of how mail servers work.
Posted by Unknown at 4/28/2016 03:36:00 PM
Saturday, July 19, 2014
Microsoft Internet Connection Sharing enables a computer connected to the Internet via a cable or DSL modem to share its connection with other computers connected to it.
- Method 1 of 2: On the Host Computer
1 Click Start, and then click Control Panel.
2 Click Network and Internet Connections, Click Network Connections.
3 Right-click the connection that you use to connect to the Internet. For example, if you connect to the Internet by using a modem, right-click the connection that you want under Dial-up.
4 Click Properties. Click the Advanced tab.
5 Under Internet Connection Sharing, select the Allow other network users to connect through this computer's Internet connection check box.
6 If you are sharing a dial-up Internet connection, select the Establish a dial-up connection whenever a computer on my network attempts to access the Internet check box if you want to permit your computer to automatically connect to the Internet.
7 Click OK. You receive a message, Click Yes.
- Method 2 of 2: On the Host Computer
1 Click Start, and then click Control Panel. Click Network and Internet Connections. Click Network Connections.
2 Right-click Local Area Connection, and then click Properties.
3 Click the General tab, click Internet Protocol (TCP/IP) in the This connection uses the following items list, and then click Properties.
4 In the Internet Protocol (TCP/IP) Properties dialog box,
click Obtain an IP address automatically (if it is not already selected), and
then click OK.
5 In the Local Area Connection Properties dialog box, click OK.
6 Open your browser to check, if what you did works..
Posted by Unknown at 7/19/2014 04:08:00 PM
Friday, July 18, 2014
This is inscrutable will show you how to shutdown a computer (from your own) remotely. there is no need to send a file sneak on their computer or have any contact with them. This requires little or no DOS skills although it will help if you are 1337
Step 1: Find their computer name
First type "net view"
Next find you target in the list (by the way the target needs to be on your network)
Congress you've found your target.
Step 2: Shutdown -i.
Go to run and type CMD. this will bring up command prompt or DOS. Type shutdown -i and a dialog should come up
Type the computer name. Then change warning time to 2 seconds and type a message if you want.
Step 4: Done
Click OK and you’re done. The most pleasing part is when you do it in an office or school computer and lab
Posted by Unknown at 7/18/2014 04:36:00 PM
Wednesday, July 16, 2014
Many people consider the Apple MacBook Air to be the gold standard in ultrathin laptops, but Windows users don't have to jump to the Mac platform to get the same slim and sleek design.
The seven lightweight laptops here are each no more than about an inch thick, and in some cases they cost several hundred dollars less than the groundbreaking Apple laptop.
Here's how these ultrathin laptops each stack up to Apple's popular 13.3-inch ultraportable (discussed in the order of their announcement).
Samsung Series 9
Advantages: The 13.3-inch Samsung Series 9 comes with twice the memory (4GB versus 2GB) of the MacBook Air. It also has a backlit keyboard, faster USB 3.0 ports, and, most important, the latest Intel processors (two generations newer than the 2010 MacBook Air). Samsung's high-style laptop is a touch thinner and lighter than the MacBook Air, too, though not noticeably so.
Disadvantages: Retailing for $1599, the Series 9 doesn't have any price advantage over the high-end MacBook Air model and costs $300 more than the lower-end Air version. The MacBook Air also has a higher display resolution (1440 by 900 pixels) than that of the Series 9 (1366 by 768 pixels).
Note: The Samsung Series 9 also comes in an 11.6-inch version to rival Apple's similar, smaller MacBook Air.
Toshiba Portege R830
Advantages: Also boasting a 13.3-inch display, the Toshiba Portege R830 (starting at $890) weighs only 0.3 pound more than the MacBook Air, yet can save you as much as $700. Like the Samsung Series 9, the Portege R830 comes with 4GB of RAM (twice the memory of the MacBook Air) and USB 3.0 ports. Its rated battery life is 2 hours longer than that of the MacBook Air and the Series 9. Perhaps most distinctive for a laptop of this size and weight: The Portege R830 comes with 4GB of RAM (twice the memory of the MacBook Air) and USB 3.0 ports. Its rated battery life is 2 hours longer than that of the MacBook Air and the Series 9. Perhaps most distinctive for a laptop of this size and weight: The Portege R830 has an integrated DVD drive.
Disadvantages: Although the Portege R830 has a larger-capacity drive (640GB), it's a slower 5400-rpm SATA hard drive rather than the premium Flash storage type found in the MacBook Air. The Portege R830's display resolution (1366 by 788 pixels) is lower than the MacBook Air's (1440 by 900 pixels), too. Finally--and most noticeably--while the MacBook Air is known for its supersleek profile, the Portege R830 has a boxier build and is about a third of an inch thicker (1.05 inches at its thickest).
MSI X-Slim X370
Advantages: If you don't mind a bit more thickness (0.2 inch) and a touch more weight (0.2 pound) to your ultraslim laptop, you can save between $700 and $1000 by buying the $599 MSI X-Slim X370 instead of the MacBook Air. This 13.4-inch machine should have a longer battery life than the MacBook Air (up to 3 hours more than the Air's 7 hours), thanks to its new AMD Fusion processor. It comes with 4GB of memory instead of 2GB, and it has an HDMI port for connecting to your TV.
Disadvantages: Though undoubtedly thin, in terms of design the X-Slim X370 isn't as cutting-edge as the MacBook Air and its aluminum unibody construction. And although the 500GB hard drive available for the X370 at retail has a faster (7200-rpm) speed than MSI previously announced, it's not the high-performing Flash storage that the MacBook Air offers. Finally, Apple has better brand recognition than MSI, which may or may not matter to you.
Posted by Unknown at 7/16/2014 09:29:00 PM
Monday, December 30, 2013
How to Take a Screenshot With an iPhone
If you want to know how to take a screenshot with your iPhone, just follow these easy steps.
1) Turn on your iPhone. Just hold down the button on the top right of the phone and wait for the white Apple logo to appear.
2) Find the image you want to capture. You can choose any image from your email, photos, home screen, or from anything you find online.
3) Find your Sleep/Wake button. This is the button on the top right of your phone. It's the button you use to turn your phone on and off.
4) Find your Home button. Your home button is the round button centered on the bottom of your iPhone. It has a picture of a white square in the center.
5) Hold down the Sleep/Wake and Home buttons at the same time and release them. If you were able to take a screenshot, then you should hear a camera shuttersound and see a white screen.
You only need to hold the two buttons down for one second for this to work.
You don't have to release the buttons at the exact same time.
6) Check your Camera Roll to make sure that you captured the image. To find your Camera Roll, simply click on the "Photos" application on your home screen. Then click on "Camera Roll," which should be listed as your first album. Your screenshot should be the last image in this album.
- If you weren't able to take the screenshot, try to do it again and hold down the buttons for a second longer this time.
Posted by Unknown at 12/30/2013 12:12:00 PM
Friday, October 18, 2013
Bacteria that makes the Hawaiian bobtail squid bioluminescent also dictate when it expresses a gene that encodes circadian rhythm-controlling proteins,according to a paper due to be published in mBio.
The squid has fascinated microbiologists for years because of its harmonious relationship with just one bacteria -- Vibrio fischeri. The bacteria does not express light when it is freely roaming in the ocean, but when housed in the squid's light organ (located in its underbelly) it will work with the animal to emit light according to how much
moonlight and sunlight is visible above. In doing so, the squid will glow a light blue to mimic the light from above, eliminating its shadow on the seabed and rendering it invisible to predators potentially lurking below. The two live a happy coexistence: the bacteria getting sustenance from the squid, the squid getting camouflage from the bacteria.
A cyclic daily routine enjoyed by the two had already been noted. For instance, the bobtail squid expels 95 percent of the bacteria every morning when it's about to go to sleep in the seabed. In doing so the squid ensures infant squid have access to new bacteria and that it stops emitting light while it sleeps. The remaining bacteria repopulate everyday and are back to full capacity by nightfall. This process employs a type of cell-to-cell communication called quorum sensing. It's induced when the individual bacteria release chemical autoinducers to alert others to its presence, and when the level of autoinducers reaches a certain density the bacteria turns on genes that react with proteins to emit the light. In the bobtail's case, the bacteria produces the enzyme luciferas. It's why the bacteria doesn't emit light outside the squid's organ -- in the ocean the autoinducers never accumulate to a high enough density.
What has been unclear is how the squid and bacteria communicate with one another -- for instance, how does the squid recognise and translate light messages to good bacteria and not bad. The mBio paper has gone a way in providing some clues as to how this symbiosis works behind the scenes. It has revealed that escry1, one of two genes in the squid that encodes proteins that set its inner clock (similar to our light sensitive biological clock) is dominant in the light organ where the bacteria thrives.
Lead author on the paper Margaret McFall-Ngai of the University of Wisconsin found that the gene was not cycling with environmental light however, as is the norm among animals and humans, but with the bioluminescence dominant at night. The find is an exciting one because it is "the first report of bacteria entraining the daily rhythms of host tissues", according to McFall-Ngai, and could be replicable in other animals or even humans. It's been difficult to breakdown the relationship between human, their good bacteria and viruses because the system is so complex -- we have millions of "good bacteria" thriving within us. Conversely, there is just one bacteria dominant in the bobtail squid and the pair make excellent research subjects because each can thrive without each other.
This means researchers can study bacteria-free squid in the lab to see what natural states the Vibrio fischeri are affecting -- which is how McFall-Ngai confirmed her suspicions about what was happening with the gene cycles.
She found that squid in the lab that lacked Vibrio fischeri bacteria could not luminesce and did not cycle their expression of the escry1 gene. Using a blue light to mimic the luminescence still did not induce gene cycling. However, if the bacteria was present but defective (unable to luminesce), gene cycling did kick in when the fake light was used. It proves that the bacteria and the light are together essential for controlling gene cycling in the squid.
Breaking the process down further McFall-Ngai found that microbe-associated molecular patterns (MAMPs), which alert animals to the presence of certain microbes, induced some cycling when combined only with light and not bacteria. Next up she and her team will investigate how the escry1 gene affects the squids metabolism, but the whole find could point us in the right direction to understanding how the millions of bacteria in our gut possibly regulate other processes in the body.
"Recently, in two different studies, biologists have found that there is profound circadian rhythm in both the epithelium [of the human gut] and the mucosal immune system of the gut that is controlled by these clock genes," McFall-Ngai said in a statement. "What are we missing? Are the bacteria affected by or inducing the cycling of the tissues with which they associate? We don't know."
Further studies of the processes could answer questions about how our body communicates with good bacteria, and how the Vibrio fischeri bacteria developed a symbiotic relationship -- considering it is closely relation to other Vibrio bacteria that are far from symbiotic, causing cholera and gastroenteritis.
Posted by Unknown at 10/18/2013 10:26:00 AM