That depends how they do it, and what they expect users to see.
Suspend the content rule, and the web site is off line. Users will not be able to connect at all.
I am presuming there are multiple servers providing the content? There are a number of way the site can stay up while they do this. I will assume they have four real servers providing the content, and that they have an alternate route - ie they do not manage the servers via the web site interface.
1. Action on their part, you do nothing.
They close down the services (ISA/Apache or whatever they use) on two of the servers, and then they upgrade the content on the two servers. As they have closed the application, the servers will go down in the CSS and the CSS will not pass any traffic to them.
When they have completed the first two, they restart the application and close it on the other two servers, do the upgrade and then bring them back. This does not allow any testing before live sees the new content.
2. Action on both of you.
You suspend two of the web servers services in the CSS, they do the upgrade. Outline is similar to above in that the CSS is no longer passing traffic to the suspended services. When complete (assuming durect access is not blocked) they can test the upgraded content by accessing the server directly. When they are happy, you activate the servers, and suspend the others for them to upgrade those.
allows a little testing, but not he effect of the upgrade on the CSS.
If the config has been defined with this sort of action in mind (internal and external content rules, duplicates of the servers for internal and external etc), and you have a sorry server, then yu could suspent the services for the external so that all external requests will be handled by the sorry server and they can upgrade and test, then when they have finished you reactivate the services and it is live.
One needs to be careful about just pulling a live web service such that it disappears. A small "private" web site will be OK, especially if the users know in advance about the change, but a large e-commerce site can have a longer impact upon business, as users may just switch to a different website, and not bother coming back.
If you need more than this, add a copy of your config, and tell us what logical server you need to close, and we may be able to hep, but you may be better doing that in the datacentre -> application networking forum as thre are a few real CSS experts that hang about.
