DNS scavenging with non-windows machines

[risproblems]

We have a LAN environment that is primarily windows based but with a few Linux machines for web services and File storage. Recently I had a problem with DNS not having Host records for a few of these machines. This is strange because I have scavenging on but I turned it on about 5 months ago. I am guessing that the records where removed because of scavenging I just don't know why it took so long. I have made some recent changes and made some of the zones AD integrated could this have caused DNS to not recognize which records where manually entered? Does DNS know if a record was manually entered or was added by DHCP?

I would like to have scavenging turned on but I don't know how to ensure my non-windows machines won't be affected. Any thoughts?