we have a mixed 2010 / 2013 environment. over the past few months we have noticed outlook clients trying to autodiscover the mailbox server and obviously failing. We have 6 cas servers and 8 mailbox servers. we have not made any changes to the environment during this time. Outlook clients are outlook 2010, 2013 and 2016.
anyone come across this before and know what the issue is ?
Thank you