At //SEIBERT/MEDIA we run our intranet based on Linchpin and Atlassian Confluence internally and the extranet in our demilitarized zone (DMZ). This is mainly because of security reasons.
With our Space Privacy add-on for Conflunence it is perfectly fine to mix internal and external content and still lock external users out from the intranet. The spaces are protected and customers can only access their own spaces and users. See this video:
To cut a long story short:
Technically you can combine intranet and extranet into one instance. We recommend two instances though.
Here are some more thoughts on two instances:
- Two instances increase the complexity.
- Two instances make it cristal clear where internal stuff is and where customer stuff is. This improves security.
Here are some more thoughts on one combined instance:
- One instance is easier for users.
- It is very easy to post something internal in the extranet so that it is available for customers. That can be awkward or even a breach of contract. This is a security thread. Especially new Confluence users are vulnerable to such mistakes.
- If you have one instance, you should use our Linchpin Theme Plugin to significantly change the layout of each space so that users easily see which are internal and which are external areas.