Hi Francesco,
Not really.But you may want to take care in the following cases.
OnCommand Server acting as trap receiver from each filer.( snmp trap host in filer)
OnCommand Server acting as trap forwarder/sender to third part trap receivers like HPOV, IBM Tivoli etc.
Both these cases many not be affected if the dns names were used and that remains same during the IP address change.
These are the top things that come to my mind.
Regards
adai