A classified ads server receives a search query from a mobile device operated by a user. The search query is parsed and a plurality of tokens is extracted from the search query. A query classification is determined based on the query, using a domain index, and query response candidates are selected from a content index based on the search query tokens and the query classification. A relevance score is generated for each of the query response candidates, and a classified ad is selected based on the relevance scores. The classified ad is sent to the user device.