If you’ve ever set up an email account before, you’ve probably been asked which email protocol you would like to use: POP or IMAP. To the uninitiated, this question can be positively mind-boggling. However, the selection that you make will have a major impact on your experience of sending, receiving and otherwise using email messages. While POP, or Post Office Protocol, used to be the most popular type of email protocol, IMAP – or Internet Message Access Protocol – is the go-to choice of most people these days. Learn more about what IMAP is, how it works, how it compares to POP and its main advantages below.
IMAP: The Basics
As its name implies, IMAP allows you to access your email messages wherever you are; much of the time, it is accessed via the Internet. Basically, email messages are stored on servers. Whenever you check your inbox, your email client contacts the server to connect you with your messages. When you read an email message using IMAP, you aren’t actually downloading or storing it on your computer; instead, you are reading it off of the server. As a result, it’s possible to check your email from several different devices without missing a thing.
Mail Servers, Email Clients and IMAP
The easiest way to understand how IMAP works is by thinking of it as an intermediary between your email client and your email server. Email servers are always used when sending and receiving email messages. With IMAP, though, they remain on the server unless you explicitly delete them from it. When you sign into an email client like Microsoft Outlook, it contacts the email server using IMAP. The headers of all of your email messages are then displayed. If you choose to read a message, it is quickly downloaded so that you can see it – emails are not downloaded unless you need to open them.
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Static IP addressing is for one customer on one IP address and Dynamic IP addressing assigns a different IP address each time the ISP customer logs on to their computer, but this is dependent upon the Internet Service Provider (ISP) because some ISP’s only change the IP address as they deem it necessary.
If you have Dynamic IP Addressing through your Website Host it means that you are sharing an IP Address with several other customers.
If you are a beginner on the internet, an avid internet user, are entertaining the thought of starting your own website business, are a gamer, use VOIP or VPN there are several things you should know about IP Addressing.
Static IP Addressing
If you feel the need to always know what your IP address is then you need a Static IP address, because it is constant. Static IP addresses are more reliable for Voice over Internet Protocol (VOIP), more reliable to host a gaming website or to play X-Box, Play Station, use Virtual Private Network for secure access to files from your company network computer, etc. Static IP addresses are also great if you use your computer as a server, as it should give your file server faster file uploads and downloads. Another plus with Static IP’s, when hosting a website you are not sharing your IP with another company who sends out a lot of E-mail SPAM and not only has their website been shut down but in turn gets your IP address blacklisted.
In contrast a static IP address can become a security risk, because the address is always the same. Static IP’s are easier to track for data mining companies. Static IP addressing is less cost effective than Dynamic IP Addressing.
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What is the Domain Name System (DNS)?
Every time you visit a website, you are interacting with the largest distributed database in the world. This massive database is collectively known as the DNS, or the Domain Name System. Without it, the Internet as we know it would be unable to function. The work that the DNS does happens so seamlessly and instantaneously that you are usually completely unaware that it’s even happening. The only time that you’ll get an inkling about what the DNS is doing is when you’re presented with an error after trying to visit a website. Learn more about what the DNS is, how it works and why it’s so critical by reading on below.
IP Addresses and Domain Names
In order to understand what the DNS is and how it works, you need to have a basic understanding of IP addresses and domain names. An IP address, or Internet Protocol address, is a complex string of numbers that acts as a binary identifier for devices across the Internet. In short, an IP address is the address that computers, servers and other devices use to identify one another online. The vast majority of IP addresses are arranged into four sets of digits – i.e., 12.34.56.78.
A domain name is the information that you enter into a web browser in order to reach a specific website. When you input a URL like www.example.com/index into a web browser, its domain name is example.com. Basically, a domain name is the human-friendly version of an IP address. Businesses vie for easy-to-remember domain names, since they make it easier for people to remember how to find them online. If people had to remember complex IP addresses in order to navigate the Internet, it wouldn’t be nearly as useful or enjoyable.
Translating Domain Names into IP Addresses
Although it’s possible to enter an IP address into a web browser into order to get to a website, it’s a lot easier to enter its domain name instead. However, computers, servers and other devices are unable to make heads or tails of domain names – they strictly rely on binary identifiers. The DNS’s job, then, is to take domain names and translate them into the IP addresses that allow machines to communicate with one another. Every domain name has at least one IP address associated with it.
Top Level Domains, Root Servers and Resolvers
The DNS is a remarkable database. It doesn’t perform its work alone, though. Things called Top Level Domains (TLDs) and root servers do a lot of the heavy lifting for the DNS. A Top Level Domain refers to the part of a domain name that comes after the period. For instance, the TLD of example.com is COM. While there’s an ever-expanding number of domain names, there’s a relatively static number of Top Level Domains; .com, .edu and .org are just a few key examples.
Specialized computers called root servers store the IP addresses of each Top Level Domain’s registries. Therefore, the first stop that the DNS makes when it resolves, or translates, a domain name is at its associated root server. From there, the requested domain name is sent along to a Domain Name Resolver, or DNR. Domain Name Resolvers, or resolvers, are located within individual Internet Service Providers and organizations. They respond to requests from root servers to find the necessary IP addresses. Since the root server already recognizes the .com, .edu or other part of the equation, it simply has to resolve the remainder of the request. It usually does this instantly, and the information is forwarded to the user’s PC.
The DNS: A Huge Distributed Database
Millions of people make changes to the DNS every day, through new domain names, changes to IP addresses and other requests. The unique structure of the DNS, though, keeps everything straight. Duplicate domain names cannot exist within domains, but they can exist across them – for instance, example.com and example.gov could be two separate locations online. Otherwise, the highly organized and efficient nature of the DNS ensures that you never have to worry about arriving at two different places each time you input a domain name. When you enter a domain name, its IP address will be resolved and you’ll always arrive at the same place. Without the DNS, the Internet wouldn’t be useful, practical or enjoyable.
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What is File Transfer Protocol (FTP)?
FTP, File Transfer Protocol, is a protocol through which internet users can upload files from their computers to a website or download files from a website to their PCs. Originated by Abhay Bhushan in 1971 for use in the military and scientific research network known as ARPANET, FTP has evolved into a protocol for far wider applications on the World Wide Web with numerous revisions throughout the years.
FTP is the easiest way to transfer files between computers via the internet, and utilizes TCP, transmission control protocol, and IP, internet protocol, systems to perform uploading and downloading tasks.
How It Works
TCP and IP are the two major protocols that keep the internet running smoothly. TCP manages data transfer while IP directs traffic to internet addresses. FTP is an underling of TCP and shuttles files back and forth between FTP server and FTP client. Because FTP requires that two ports be open–the server’s and the client’s–it facilitates the exchange of large files of information.
First, you as client make a TCP control connection to the FTP server’s port 21 which will remain open during the transfer process. In response, the FTP server opens a second connection that is the data connection from the server’s port 20 to your computer.
Using the standard active mode of FTP, your computer communicates the port number where it will stand by to receive information from the controller and the IP address–internet location–from which or to which you want files to be transferred.
If you are using a public–or anonymous–FTP server, you will not need proprietary sign-in information to make a file transfer, but you may be asked to enter your email address. If you are using a private FTP server, however, you must sign in with a user name and password to initiate the exchange of data.
Modes of File Transfer
Three modes of transferring data are available via FTP. The system can use a stream mode, in which it transfers files as a continuous stream from port to port with no intervention or processing of information into different formats. For example, in a transfer of data between two computers with identical operating systems, FTP does not need to modify the files.
In block mode, FTP divides the data to be transferred into blocks of information, each with a header, byte count, and data field. In the third mode of transfer, the compressed mode, FTP compresses the files by encoding them. Often these modifications of data are necessary for successful transfer because the file sender and file receiver do not have compatible data storage systems.
Passive FTP
Should your computer have firewall protection, you may have difficulties using FTP. A firewall protects your PC by preventing internet sites from initiating file transfers. You can circumvent your firewall’s function by using the PASV command that reverses the FTP process, allowing your computer to initiate the transfer request.
Many corporate networks use PASV FTP as a security measure to protect their internal network from assaults of unwanted external files. Also called passive FTP, the process requires that any transfer of information from the internet or other external source must be initiated by the client or private network rather than the external source.
Further FTP Security
In response to the need for a more secure transfer process for sensitive information such as financial data, Netscape developed a Secure Sockets Layer (SSL) protocol in 1994 that it used primarily to secure HTTP–HyperText Transfer Protocol–transmissions from tampering and eavesdropping. The industry subsequently applied this security protocol to FTP transfers, developing SFTP, a file transfer protocol armored with SSL for protection from hackers.
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Internet Protokol Version 6 (Türkçe: Internet Protokol sürüm 6) kısaca IPv6, 32 bitlik bir adres yapısına sahip olan IPv4′ün adreslemede artık yetersiz kalması ve ciddi sıkıntılar meydana getirmesi üzerine geliştirilmiştir.
IPv4 oluşturulmaya başlandığında İnternet’in bu kadar ilerleyeceği hesap edilmemişti. Şimdi adresleme sıkıntısı oluşunca 128 bitlik adres yapısı olan IPv6′ya geçilmesi kaçınılmaz olmuştur. Bu sefer gelecek fazlasıyla düşünülerek oluşturulmuş bir adres yapısıdır. Yeni adreslemede sınırsız denebilecek bir adres aralığı olacaktır.
IPv6′da olan trafik işgal edici paket başlıkları kaldırılarak bir hız arttırımına gidilmiştir. Ayrıca yeni eklenen şifreleme sistemleriyle daha güvenli iletimler sağlanmaktadır. Uçlar arasında şifreli iletimi kolaylaştıran AH ve ESP başlıkları mevcuttur. AH ve ESP başlıkları uçlar arasındaki tüm veri iletimini şifreleyen IPSec protokolünü desteklemek amaçlı kullanılmıştır.
Ayrıca şu anda IPv4′ün, QoS eklentisiyle idare ettiği ama tam olarak destekleyemediği görüntü ve ses iletimi sıkıntısı IPv6 ile çözülecektir. IPv6, görüntü ve ses paketlerine “öncelikli pakettir” ibaresi atanarak bunlara trafikte öncelik tanımasına olanak sağlamaktadır.
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What is Simple Mail Transfer Protocol (SMTP)?
SMTP stands for Simple Mail Transfer Protocol. It’s a set of communication guidelines that allow software to transmit email over the Internet. Most email software is designed to use SMTP for communication purposes when sending email, and It only works for outgoing messages. When people set up their email programs, they will typically have to give the address of their Internet service provider’s SMTP server for outgoing mail. There are two other protocols – POP3 and IMAP – that are used for retrieving and storing email.
SMTP provides a set of codes that simplify the communication of email messages between servers. It’s a kind of shorthand that allows a server to break up different parts of a message into categories the other server can understand. Any email message has a sender, a recipient – or sometimes multiple recipients – a message body, and usually a title heading. From the perspective of users, when they write an email message, they see the slick interface of their email software, but once that message goes out on the Internet, everything is turned into strings of text. This text is separated by code words or numbers that identify the purpose of each section. SMTP provides those codes, and email server software is designed to understand what they mean.
The other purpose of SMTP is to set up communication rules between servers. For example, servers have a way of identifying themselves and announcing what kind of communication they are trying to perform. There are also ways to handle errors, including common things like incorrect email addresses. In a typical SMTP transaction, a server will identify itself, and announce the kind of operation it is trying to perform. The other server will authorize the operation, and the message will be sent. If the recipient address is wrong, or if there is some other problem, the receiving server may reply with an error message of some kind.
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