---Quote on---
One commenter commented that the requirement that the statement
appear on the home page of a Web site is vague because many web sites
operate with subdomains, making the actual homepage or principal URL
difficult to identify. The Department declines to adopt this comment.
Subdomains, as the name implies, are URLs that share the top-level
domain name's basic URL and have additional identifying address
information to provide additional content on a separate Web page. Each
subdomain thus has its own homepage
and each homepage must feature the statement. For example,
http://www.usdoj.gov is the full domain name of the Web site of the Department
of Justice.
http://www.usdoj.gov/criminal is the Web page of the Criminal Division, which is hosted by the Department's Web site.
Under this rule,
http://www.usdoj.gov would be required to have a statement and that statement would cover anything contained on
http://www.usdoj.gov/criminal.
However,
http://www.ojp.usdoj.gov is a
subdomain of the full domain
http://www.usdoj.gov and would be required to have its own statement on that page, which would then cover any
material on a Web page linked to it, such as
http://www.ojp.usdoj.gov/ovc/
, the Web page of the Office for Victims of Crime.
---end quote---
The way I read the above it seems that you only need one compliance notice per domain and one per subdomain.
So long as all the content contained on those domains is compliant.