As the name says, dedicated server means you will get a dedicated computer which hosts only your own applications and web sites. The hosting company will give you a computer with all required softwares like IIS, operating system etc. You may have to pay additional fee to get optional features like anti virus, firewall, SQL Server etc.
You will be allowed to access the dedicated server remotely using some tools like "Terminal Services". Such tools will allow you to specify the IP Address of your dedicated server (which is sitting in the data center of the hosting company) and login to the server. Once you login to the server, you will see the desktop of the server instead of your own local computer. You can do virtually everything that you, can as if you are sitting in front of the server itself.
The way the Terminal Service or any other remote administration works is, they will have a software running on the server. You have to install a client version of the same software in your PC. To access the remote server, you have to launch the client software. The client software will communicate with the server software in the remote machine. These two softwares will communicate each other and provide you a screen to login to the server. Once you logged in, the client machine will get the server screen and display to you exactly like what you would have seen if you were in front of the server. Whatever commands you do in the screen, the client software will send the inforation to the server software in the remote machine. The server software will execute the commands on the remote server. So, you will feel that you are working directly on the remote machine, even though it will be much slower compared to you are working on a PC directly.
The remote login requires that a server software must be installed on the server and a client software installed on your PC. The most commonly used remote access system is "Terminal Services" which is provided by Microsoft as an optional feature when you install Windows operating system.
How to access a dedicated server, if the server is OFF ?
There is no way you can communicate with the server if it is shutdown or power off. Your remote access client software connot retrieve the server screen or send commands to it. It will work only if the server is on and remote server software is running in the server.
The only way you can get the server running if it is switched off is, contact the hosting company and ask them to start the machine manually. Once the machine is started, the server software will automatically start since they will be configured as Auto start windows service.
The remote access client software will allow you to shutdown or restart the server. If you restart the server, your connection with server will be automatically lost temporarily. But once the server is restarted, you can connect again. But If you shutdown remotely, you cannot connect or start any more until some one go to the server and start manually.
Managed hosting and un managed hosting
Most dedicated hosting plans offer 2 different options - managed and un managed.
Managed hosting plans
Managed option means the hosting company will take care of managing the server. This includes backing up the data at regular intervals, running all windows service packs and updates whenever available, scanning for virus etc. There may be an additional fee for this.
Also, in case of managed dedicated hosting, your control may be limited. They may not want you to change all settings and mess up the machine. If you mess up something, still you are going to call them and ask "why is my server down?". Since they don't this, they will limit your accees rights on your server, even though you are allowed to remotely access the server.
Un managed dedicated hosting plans
In this plan, the hosting company will not manage your server. They will simply install all required softwares and give you remote access. Then onwards it is your responsibility to manage everything. If you mess up your server settings, they may not help you to resolve the issue.
What software can be installed on dedicated server ?
It is your machine and you can install any software you want. Some hosting comapnies may ask you to show licensing documents if you install copyrighted software like SQL Server etc.
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