DRAG DROP
A company deploys an Office 365 tenant. All employees use Lync Online.
You need to configure the network firewall to support Lync Online.
Which ports must you open? To answer, drag the appropriate port number to the correct feature or
features. Each port number may be used once, more than once, or not at all. You may need to drag
the split bar between panes or scroll to view content.
Explanation:
http://onlinehelp.microsoft.com/en-ca/office365-enterprises/hh416761.aspx
Tricky one, Lync Online needs 443 AND 3478 for Audio / Video
5223 for push is definitely right
https://ahandyblog.wordpress.com/cloud-technologies/firewall-ports-for-office-365/
Question specifies ‘sharing sessions’ therefore the correct answer is 443
https://support.office.com/en-gb/article/Set-up-your-network-for-Skype-for-Business-Online-operated-by-21Vianet-d21f89b0-3afc-432e-b735-036b2432fdbf