The Canadian Internet Registration Authority (CIRA) maintains a list of reserved names that are not available for registration in the .CA registry. This list includes the following:

• All existing country code top-level domains (ccTLD) two letter names as recognized by the Internet Corporation for Assigned Names and Numbers (ICANN), (including ca.ca and us.us) and all the existing generic top-level domain (gTLD) three letter names (including .com.ca, .org.ca, .net.ca, .edu.ca, .gov.ca, .int.ca, .mil.ca). CIRA will reserve .mil.ca for, and register .mil.ca in the name of the Canadian Federal Government Department of National Defense;
• The following names: village.ca, hamlet.ca, town.ca, city.ca and ville.ca;
• Such domain names that are at the relevant time, available for registration as CIRA may determine in it's sole discretion;
• The names, and all abbreviations of names of Canada, of Canadian provinces and territories as well as the names of major Canadian cities and landmarks. CIRA uses the Canadian Geographical Names Database (CGNDB) under licence from Natural Resources Canada. The terms of the licence do not permit CIRA to disclose the data to others. Interested persons may obtain a licence of the CGNDB by contacting the Natural Resources Canada. CIRA reserves the right to periodically review and amend this list and to grant registrations of any names on the list as it deems appropriate.
• Georgraphical names may be made available to corresponding government entities under special condictions to be determined by CIRA in it's discretion.

Only second-level (ex: mydomain.ca) registrations are available. CIRA will allow any existing third or fourth-level .CA domains to continue to be renewed by their current registrant.