Hi,

I having two questions:

1. Is it necessary that all SQL servers contains same instance names (If in case namedinstance), if different names what will be the impact?

2. Is it possible to rename listener?

Can you clarify what you mean by AlwaysOn as this is a marketing term? If you mean Availability Groups, then, you can use different instance names across all replicas. However, I wouldn't recommend that for the purpose of standardization and operational efficiency. Also, it is possible to rename a listener name. You just need to coordinate with your network administrators to make sure that the DNS entry is unique in your environment