I encourage you to walk through this in your labs for a detailed dry run of your production installation.
Reference lab you build out from the document listed here. You can optionally install Edge for external testing, etc.
Very nice step by step procedures for installing Lync Server into your non-production lab.
Grab the Lync Server 2010 Step by Step lab installation guide here.
Grab Lync Server 2010 release candidate bits here.
Thank you for sharing. I read through the document found that page 12 and page 15 for the external DNS are not same.is that mis typing or you have modified the DNS IP?
It probably was a typo. I recommend using the RTM deployment guide rather than this since it was based on Release Candidate code: