Your options will depend on which Registrar/DDNS service you choose to use.

If you are interested in registering a TLD, a list of approved registrars can be found here: http://www.internic.net/regist.html

You also have an alternative option to registering a standard domain name, which would provide you the ability to have a domain alias for free.

Companies, such as DynDNS and No-IP.com, offer free domain aliases for numerous domain names that they own. You could, for instance, register sarahsplace.dyndns.org or billy.no-ip.com.

These free domain alias services are usually targeted at users that have a Dynamic IP Address, but can just as easily be used if you have a truly Static IP Address. Both DynDNS and No-IP.com offer Dynamic IP Address Update Clients, that run on your computer and monitor changes to your IP Address. If your IP Address changes, the client will automatically update your DNS record, so that your domain name will always point to your computer. Some routers have this update client built into the router. If your router has support for your Dynamic DNS (DDNS) provider, and you configure your router to process your IP Address changes; you will not have to run the software-based update client on your computer.

See also InterNIC's FAQ on Domain Names, Registrars, and Registration

Routers

If there is only one computer in your home, you most likely do not have the need for a router. If you are using a cable or DSL modem, your setup (or network topology) might look like the diagram in Figure A.

In Figure A, Internet traffic flows directly to your computer. The IP Address that is assigned by your ISP is assigned to your computer. Unless your modem has additional, built-in NAT features, nothing prevents traffic from reaching your computer, save a firewall.

If you have more than one computer, you may be using a wired router to share your Internet connection, and your network topology might look like the diagram in Figure B.

In Figure B, the IP Address assigned by your ISP is assigned to the router, not your computer. Your router, in-turn, assigns internal network IP Addresss to each computer in the network, so that Internet traffic gets routed properly. IP Addresss that start with 192.168 are reserved for internal networks only and are not used by the Internet.

The IP Address assigned to your router is known as your Internet IP Address or WAN IP Address. This IP Address is used for Internet communications. The IP Address assigned to the computers on your network are known as LAN IP Addresses, Internal IP Addresses or Private IP Addresses. Your router is also assigned a LAN IP Address, which is typically used by you to access its web-based configuration. The Internal/LAN IP Addresses are used for communications within your Local Area Network (LAN) only, and mean nothing to the outside world.

Figure A	Figure B

Port Forwarding

For the following explanation, it is easiest to compare your Internet connection with a highway, or superhighway, with traffic heading in both directions and in many lanes. Each side of the highway has lanes that are for specific traffic only, such as a carpool lane or a public transportation lane. In our examples, each lane represents a particular port number. Certain types of Internet traffic use specific port numbers. Web pages (HTTP) travel on port 80, files transferred via FTP (File Transfer Protocol) on port 21, email (communication with your ISP's mail server) on ports 25 and 110, and BitTorrent trackers on port 6969 (default).

If you have a router, this highway goes through it before reaching your computer. Therefore, when you type google.com in your web browser, a request is sent to your router. The router takes note of which computer is requesting the webpage (using your computer's LAN IP Address), so that the webpage requested is sent back to your computer, and not to another one on your LAN, thus "routing" the data properly. Routers usually handle your Internet (Outbound Access) file requests automatically and do not require additional configuration.

If, however, you are running a web server or another server application (FTP Server, BitTorrent Tracker, etc), you will need to tell the router, from which computer that data will be sent (served), so that when Inbound Access Requests for data are received, the requests get routed properly to the computer that is running the service.

If you were running a web server on your computer, the data (webpages, images, etc) would be sent out to visitors on port 80. If your computer's Internal IP Address was 192.168.1.2, you would need to tell your router to forward all inbound access on port 80 to that Internal IP Address.

When you are downloading a file (or files) using a BitTorrent client, you are also uploading the pieces of the file(s) that you already have downloaded. Because BitTorrent traffic is bi-directional, you will need to configure your router to forward incoming packet requests to your individual computer, to optimize the number of connections with other peers. BitTorrent uses one port number (lane) per torrent. The default port numbers are 6881 through 6999, allowing for 118 torrents to be going simultaneously. Downloading (or uploading) this many torrents is most likely impossible for your computer. You should however be sure to configure your BitTorrent client with the same min and max ports that you specify in your router's port forwarding configuration.

Many BitTorrent trackers (servers) use port 6969 to communicate with the swarm of peers (clients). If you are running a BitTorrent tracker you will need to make sure that incoming traffic is routed/forwarded properly. Because 6969 falls between 6881 and 6999, you do NOT have to specify this port separately, if you have already configured the default port range for BitTorrent in your router's configuration.

For more specific instructions regarding your router's port forwarding configuration, please refer to your router's manual, its manufacturer's website, or visit portforward.com.

Port Forwarding when Using BitTorrent on More Than One Computer

If you plan to use BitTorrent on more than one computer in your home, you will need to configure a range of ports to be used for each computer. You should have already configured the default port range (6881 - 6999) to be forwarded to your first computer (Computer #1). This port range is also specified in your BitTorrent client's configuration.

You will then need to specify a separate port range within the BitTorrent client's configuration on your second computer (Computer #2). For instance, you could use ports 7001 through 7050 for Computer #2. In addition to setting this port range in Computer #2's client, you will need to forward incoming traffic for those ports in your router's configuration.

You can continue this procedure for each computer that will be using BitTorrent.

Note: If you are not running a BitTorrent tracker on Computer #1, but you are running one on a different computer; be sure that your primary port range does not include the port number used by your tracker (6969). In this example, Computer #1 could be configured to use ports 6881-6950. Be sure to mirror any changes to your router's port forwarding in the BitTorrent client's configuration on each computer that uses BT.

Visiting Your Own Website or Tracker

Let's say you registered bluebox.com as your domain. To visit your website, you should be able to simply type bluebox.com like the rest of the world. If you were running a tracker on port 6969, you should be able to visit your tracker at http://bluebox.com:6969/

This, however, is not always the case because some routers have issues with a process known as loopback.

Normally, when you type bluebox.com, your computer/router would make a connection with your ISPs DNS server and retrieve the associated Internet IP Address for that domain and then take you back to your computer. Routers that don't support loopback make this impossible, but there is a work-around.

The HOSTS File

The following addresses will ALWAYS take you to your computer: localhost and 127.0.0.1, without ever venturing out onto the Internet and leaving your home network. If you computer's LAN IP Address is 192.168.1.2, this IP Address will also take you to your computer. If, however, your router assigns a different LAN IP Address to your computer, the latter won't work, while the former 2 will always work.

If you cannot get to your site using your domain name or your Internet IP Address, you can configure your computer to NOT USE your ISP's DNS servers by modifying your computer's HOSTS file.

If you have no problems reaching your site using your domain name, do not modify your HOSTS file.

Both Windows™ and Linux/Unix have support for this file. Depending on your operating system, it can be found in the following locations:

Windows 98/ME	C:\WINDOWS\
Windows XP and Server 2003	C:\WINDOWS\SYSTEM32\DRIVERS\ETC\
Windows 2000	C:\WINNT\SYSTEM32\DRIVERS\ETC\
Linux or Unix	/ETC/

Your HOSTS file should always be edited with a plain text editor, such as Windows™ Notepad. When saving changes, be sure to not include the txt file extension and to select "All Files" for the Save as type: option.

The HOSTS file contains a simple list of hostnames (domain names) and their associated IP Addresss. Your computer, by default, will use any listings in this file before using your ISPs DNS servers. Most HOSTS files already include one mapping, for the localhost hostname and associate it with 127.0.0.1, which is ALWAYS your computer, as explained above.

Each mapping is placed on its own line and must have at least one space between the IP Address and the hostname. Using bluebox.com as your domain/hostname, you would add the following on the line after localhost:

Now, when you type bluebox.com, your computer will seemlessly take you to 127.0.0.1, without ever using your Internet connection.

Please also read the topic regarding How to Seed Your Torrent For Others, paying particular attention to section #4 and TEST #2.