A Unique IP is an IP address that is specific to your domain. When you add hosting to a domain/subdomain, it’s assigned an IP on the Apache server which is shared with other sites. This shared IP address is most often the only IP you’ll need. However, certain applications may require adding a Unique IP to your site. You can add a Unique IP to any Fully Hosted domain/subdomain hosted at DreamHost on the Manage Websites page.
One IP per domain/subdomain
When you purchase a Unique IP, it is only applied to a single domain or subdomain. If you would like a Unique IP address for your domain (example.com) and subdomain (blog.example.com), you would need to purchase a separate Unique IP for each.
Static IP Addresses
DreamHost is unable to offer static IP addresses. This means that the IP of your site (including Unique IPs) are subject to change if necessary. DreamHost makes no guarantees that an IP address will never change. However, when an IP change occurs, you will be notified via email promptly.
Do I need a Unique IP?
In most cases, no. Unique IPs are most commonly used with domains with an SSL certificate enabled. It is possible to use secure hosting without a Unique IP, but some older browsers which do not support Server Name Indication will display a certificate warning when viewing your site. While not a comprehensive list, this includes:
- Windows XP versions of Internet Explorer.
- The default browser in Android 2.4 "Gingerbread" and earlier. (4.0 "Ice Cream Sandwich" and later will work correctly.)
- Various older mobile browsers, including BlackBerry, Symbian OS, and older versions of Opera Mobile.
While very unlikely, if you expect a significant number of visitors to your secure site to use these browsers, you will need a Unique IP. View the following link for the most commonly used browsers by year:
Unique IPs are only for websites. Adding a Unique IP will not affect your mail service since your mail is on a completely different machine. There is currently no way to adjust the IP address of a mail server.
Other use cases
A Unique IP is necessary:
- if you are interested in accessing the site directly with an IP address (this is useful when the domain in question is not yet using DreamHost's nameservers/DNS records). If you attempt to access your site through the shared server IP, the DreamHost ‘Site Not Found’ page opens, which you can read about in the following article:
- if another domain hosted on the same shared IP as yours is blocked by certain restrictive firewalls (e.g., GFW), adding a Unique IP address to the site may help it to bypass filtering (assuming the filter is based on the shared IP). This approach may also be of interest if you want to be sure your site is not associated with other sites, regardless of the presence of filters. An example of this can be found in the ‘China Firewall’ article:
Does a Unique IP help my page rank?
No, it does not. With the current shortage of IPv4 addresses as the adoption of IPv6 continues (and there is an extra cost associated with adding them to your domains), it's important to know that adding a Unique IP to your domain will not affect its search engine ranking.
If this is the only motivation to add an IP to your domain, then there is no need to add one.