exchange 2013 co existance questions

I have installed 2 exchange 2013 servers and created a dag
im in co-existence with my 2010 server
I have set all the urls to be the same i.e  /oab etc
I am using a test laptop and have configured the hosts file manually to point at the new exchange servers for testing.
I have some questions
1. if I have 2 servers can I still send / receive email if one goes down?
2. do I need to configure anything extra in the send / receive connectors
3. when using load balancers when 1 server goes down will it automatically switch over 2 the second server so that I can send / receive mail
4. is there any size restrictions for databases inside a DAG
5. now that there is no dedicated unified messaging server id this just managed from control panel
 any other advice I should know before trying to move my users from 2010 to 2013
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Scott CSenior EngineerCommented:
1.  Yes, that is the purpose of high availability

2.  You shouldn't.

3.  Yes, if your LB is configured correctly.

4.  None other than specified limitations and disk space.

5.  If I understand this question correctly, no, shouldn't need to be anything else to do before migrating.  Of course, use a test users first, then a small test base to make sure.

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Will SzymkowskiSenior Solution ArchitectCommented:
Answers below...
1 - if you have load balancing enabled then yes you will be able to send/receive email if it goes down. However if you only have one CAS server for Exchange 2010 then if the 2010 CAS server goes down users on the 2010 server will not be able to connect to their mailboxes. You cannot load balancing 2010 and 2013 CAS servers together.

2 - you need to create new send connectors on the Exchange 2013 servers to point to your smarthost. You also need to NAT your Load Balanced IP for 2013 CAS through the Firewall.

3 - depending on the type of load balancing you are using for your CAS Lay4 or Layer7 it will automatically failover. If you are using WNLB this does not work correctly all the time and you have to have the Exchange 2013 roles separated for running DAG, which is also not recommended.

4 - Size restrictions and the amount of mounted databases are based on the version of Exchange. Enterprise or Standard. Enterprise = 100 standard = 5.

5 - Use Exchange Deployment Assistant

dougdogAuthor Commented:
the send connectors look to have been automatically populated during the 2013 install
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