Domains field in Matomo Configuration variable

I am switching from Matomo’s default js tracker to a unique solution using Matomo Tag Manager. I have configured the various sites that I manage in Matomo in a single container that I will use for all sites, modifying the Matomo Configuration variable I see that there is the “Domains” field. Is it necessary to enter the domain of the main site here, or is it exclusively for entering additional domains different from the main domain (for cross-domain functionality)? If there are no other domains to add besides that of the main site (already present in the configuration of each site) can it be left empty?

Hi @Lotar
As described in the hint on the right side, domain(s) is/are used to be able to track outlinks (links with target outside your website).

Hi Philippe
Yes, ok.
If i understand correctly if i add domains here the link will NOT be treated as outlink. My question is… don’t i need to add here the main hostname of the website, is it correct?
i want to track and i have configured it as a site in Matomo.
I don’t need to add here as Matomo already consider and as a local link. Is it correct?
Here i have to add… ie. if i don’t want that this subdomain is considered outlink. So it’s a cross-domain feature and it works when I add the same tag in

I think it’s obvious, sorry for the question, but it’s just to be sure of it.
Or maybe i’m wrong… if it’s so could you please give me some use case examples?

Hi @Lotar

This is also my understanding…