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domain name system - Performance penalty when using CNAME

We are using the current CNAME record for a server, i.e.



 foo.example.com => CNAME => server1.example.com 
 server1.example.com => CNAME => ec2-34-142-138-31.compute-1.amazonaws.com 
 ec2-34-142-138-31.compute-1.amazonaws.com => A => 34.142.138.31



  1. Is this configuration common?

  2. Is the performance penalty when using 2 CNAME records critical?


  3. To minimize the impact of CNAME lookup, should I set a larger TTL for the 1st CNAME, but shorter CNAME for the 2nd CNAME?



i.e.



 foo.example.com => CNAME (TTL=86400) => server1.example.com 
 server1.example.com => CNAME (TTL=300) => ec2-34-142-138-31.compute-1.amazonaws.com

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