Yes it's necessary: BrandIEUsingUnattended Specifies whether to use Unattend.txt or an .ins file to brand Internet Explorer during an unattended Setup. Syntax BrandIEUsingUnattended = Yes | No Values Yes Brands the browser settings by using the entries specified in the browser-specific sections of the answer file: [FavoritesEx], [Proxy], and . No Uses the .ins file specified in IEBrandingFile. Info from ref.chm @ MS deploy.cab