IIS 7 automatically makes history snapshots of ApplicationHost.config each time a change is detected. By default, IIS checks for a new version every 2 minutes and will keep 10 prior versions of the file. IIS7 stores these snapshots in the %systemdrive%\inetpub\history folder by default. You can change any of these settings by editing the <system.applicationHost/configHistory> section in ApplicationHost.config.

In order to backup IIS configuration, you will have to just run the following command:

%windir%\system32\inetsrv\appcmd.exe add backup "Backup-Name"

In order to restore IIS config file backup, run this command:

%windir%\system32\inetsrv\appcmd.exe restore backup "Backup-Name"

To get list of backups and configuration history files, run following command:

%windir%\system32\inetsrv\appcmd.exe list backup