Which of the following extension file have NOT a thumbnails? Select One.

Alfresco's thumbnail service generates visual previews for content that can be rendered, such as documents, images, and videos. By default, Alfresco creates thumbnails for PDF and Microsoft Office (DOC) files by transforming their first page into an image. However, archive formats like TAR (.tar) and ZIP (.zip) are treated as containers. Alfresco does not generate a content-based visual thumbnail for the archive file itself. Instead, it displays a generic icon based on the file's MIME type, which is distinct from a content-derived thumbnail preview. Therefore, both TAR and ZIP files do not have thumbnails in the context of a visual preview.

A. PDF: Alfresco uses its built-in PDF Renderer or a configured ImageMagick transformer to generate a visual thumbnail of the first page of a PDF document.

D. DOC: Alfresco leverages an integrated LibreOffice/OpenOffice transformation service to render a preview and create a thumbnail for Microsoft Word documents by default.

1. Alfresco Content Services 7.4 Official Documentation, "Thumbnail Management": This document explains how thumbnails are defined and generated. The default configurations in thumbnail-definitions.xml include specific rules for renderable MIME types like application/pdf and those handled by LibreOffice (e.g., application/msword), but not for archive types like application/x-tar or application/zip.

Reference: Alfresco Content Services 7.4.0 Documentation > Administering > Managing transformations > Thumbnail management.

2. Alfresco Content Services 7.4 Official Documentation, "Supported transformations": This documentation provides a list of out-of-the-box transformations. It confirms that transformations from PDF and DOC to image formats (like PNG for thumbnails) are supported. It does not list any supported transformation from TAR or ZIP archives to an image format.

Reference: Alfresco Content Services 7.4.0 Documentation > Administering > Managing transformations > Supported transformations.

3. Alfresco Community Source Code, thumbnail-definitions.xml: Examination of the default configuration file within the Alfresco repository source code confirms the absence of thumbnail definitions for the MIME types application/x-tar and application/zip. These file types fall back to a default behavior, which does not create a content preview.

Reference: alfresco-repository/src/main/resources/alfresco/thumbnail/thumbnail-definitions.xml in the official Alfresco source code repository.