ftp.dell.com is migrated to downloads.dell.com. You can try below link [URL] 
I have an M610 blade with iDRAC 2.20 that I'm trying to upgrade to a more recent version, and after a lot of trial and errors, I found a document ( [URL] ) stating that I'll need to upgrade to 2.3 or 2.31 first. However, those versions are nowhere to be found. Apparently, it used to be at ftp://ftp.dell.com/esm/M610-M710-M910_iDRAC6_2.31_A00.exe before ftp.dell.com was retired.Also, [URL] says that DRM has support for 11G servers, but it seems that's gone from the current catalog too.Yes, I'm aware this is old hardware, but it works perfectly otherwise, so I'm really unwilling to just toss it. Does anyone still have a copy of that firmware version lying around?
Updating old M610 iDRAC fails