hi , 

i have currently exchange 2013 running on two node EXCH01(CAS/Mailbox) and EXCH02(CAS/Mailbox) and we are planning to add another Exchange node on DR site , the new Exchange Node will have all the role together . is there any concern i need to keep in mind before proceed with  my deployment ? for me i will do the following :

Install the new exchange server 

add new exchange server to mailbox DAG 

add new exchange server to NLB

configure send/receive connector

is there any other things i have to care about .?

thanks all 

Hi

Are you going to have your witness server in a 3rd site and are you going to look at DAC mode at all and an alternate witness?

hi , 

thanks for your reply , i have two site the main site and the DR site , what do you mean by ( are you going to look at DAC mode at all and an alternate witness? ) 

DAG and NLB is already set and configured what is need to do is to add the new Exchange node to both DAG and NLB

Hi

DAC (Data Center Activation Coordination) will stop the split-brain syndrome between a stretched DAG like you have, meaning if you lose DC1 and the DB's activate on the secondary DC, when DC1 comes back online and as it is where quorum will be due to the witness server you wont have the DB's trying to mount there either.