The Repeat Type dropdown controls whether a crawl is a repeating crawl or not, and if so, what is its repeat duration. A non-repeating crawl has one index and crawling continues adding to this index until all allowed urls have been crawled or until the administrator stops the crawl. In a non-repeating crawl one has a double index, that consists of a index to serve search results from and an index to crawl into. Once the repeat time has been exceeded the index that was being crawled into becomes the index to serve results from, the previous search index is reset to empty and is then used to crawl into for the next repeat time amount of time. The Two Minute repeat type can be used to experiment with this behavior.