AdDomains.ptxt and AdHost.ptxt

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What are their differences in functionality or usage?

[sidki3003]

Say a page is calling an external script with a "src" attribute of "http://adsv7.myads.serving.com/1.js".
"adsv7.myads.serving.com" would then be the FQDN, "adsv7" the host name, "myads.serving.com" the domain components.

AdHosts entries consist of mandatory host names, optionally followed by domain components.
AdDomains entries consist of mandatory domain components, optionally preceded by host names.

So, a "myads" AdHosts entry wouldn't match above URL, while a similar AdDomains entry would match.
An "adsv7.myads" entry would match if in AdHosts, or if in AdDomains and called by an off-domain resource.
(AdDomains entries aren't permitted to match on-domain URLs, but that's another story.)

[whileloop]

Now I understand.
Thank you for your explanation.