Host Attribute tables give you the ability to define what your network is to Snort. Snort’s host attribute table is an XML formatted file that Snort will read in and auto-configure several aspects of the preprocessors and rule technology dependent on the definitions of this file. Much easier to define your network in a file, allowing the administrator to copy just one file from an old installation to a new installation with all the host specific settings intact. The question I receive most often in my consulting with Sourcefire and Snort clients is also the easiest to field.”]
Source: https://www.csoonline.com/article/2124860/tuning-snort-with-host-attribute-tables.html