Internal outlook client connectivity in exchange 2010 when coexist with exchange 2013

Question

Hi all ,
on my side i would like to clarify few queries.
Say for instance i am coexisting exchange 2010 with exchange 2013 .Unfortunately if all of my exchange 2013 servers goes down .
Q1 .On that time will the internal outlook users having their mailboxes on exchange 2010 can be able to connect mailboxes without any issues ? In case if they face any issues what kind of issues will they be? Because why i am asking is we should have pointed
the autodiscover service to exchange 2013 during coexistence.
When an user closes and reopens the outlook after whole exchange 2013 environment failure ,outlook will first query the autodiscover service for the profile changes to get it updated on users outlook profile.In such case autodiscover service will not be
reachable and i wanted to know will that affects the internal client connectivity for outlook users having their mailboxes on exchange 2010.
Q2. Apart from outlook internal users connectivity ,what kind of exchange services(i.e owa,active sync,pop,external OA and imap) will get affected when whole exchange 2013 environment goes down during coexistence ?
I have read the below mentioned statement on this awesome blog but still i wanted to clarify with you all on my scenario.
http://blogs.technet.com/b/exchange/archive/2014/03/12/client-connectivity-in-an-exchange-2013-coexistence-environment.aspx<o:p></o:p>
Internal Outlook Connectivity
For internal Outlook clients using RPC/TCP connectivity whose mailboxes exist on Exchange 2010, they will still connect to the Exchange 2010 RPC Client Access array endpoint.
For internal Outlook clients using RPC/TCP connectivity whose mailboxes exist on Exchange 2007, they will still connect directly to the Exchange 2007 Mailbox server instance hosting the mailbox.
Please share me your suggestions and that would help me a lot .
Regards
S.Nithyanandham

Answer 1

Hi Winnie Liang ,
Thanks a lot for your reply.
Scenario  1 : for internal outlook connectivity 
We have below settings for exchange 2010 autodiscover.
mail.domain.com - will be the namespace for internal autodiscover URI for all the exchange 2010 cas serves
We are going to have below settings for exchange 2013 autodiscover.
mail.domain.com - will be the namespace for internal autodiscover URI for all the exchange 2013 cas serves
During coexistence mail.domain.com will be pointed to exchange 2013 cas servers . I mean to say if we try to resolve the mail.domain.com it will get resolved in to the exchange 2013 cas servers.
So on such case if anything happened wrong to the new environment or else if entire environment goes down .Do we face any issues while outlook users connect to existing mailboxes in exchange 2010 ?
Because why i am asking is ,on the below mentioned article i have read all the autodiscover request will go via exchange 2013 cas servers during coexistence.That means all the existing mailboxes in exchange 2010 will also have to query exchange 2013 cas
servers for autodiscover request.During the whole exchange 2013 environemnt failure whenever the user tries to close and open outlook .Outlook will first queries the autodiscover service for any changes happened on that particular mailbox and it will try to
get it updated on user profile.
http://blogs.technet.com/b/exchange/archive/2014/03/12/client-connectivity-in-an-exchange-2013-coexistence-environment.aspx
Would it be possible to make the exchange 2010 mailbox users to query only the scp points which belongs to the exchange 2010 cas servers for autodiscover request ?
Scenario 2: For exchange services
mail.domain.com - will be the namespace for all the exchange 2010 services (i.e owa,activesync,external outlook anywhere,pop,imap)
mail.domain.com - will be the namespace for all the exchange 2013 services (i.e owa,activesync,external outlook anywhere,pop,imap)
What about the above services will it get affected during whole exchange 2013 environment failure ?
Note : We are not facing this issue , i hope everything goes well in my environment while doing coexistence i am just asking this question on my own interest?
Regards
S.Nithyanandham
Thanks S.Nithyanandham