Methods and systems for range matching. The system holds a definition of one or more ranges of Internet Protocol (IP) addresses. The definition may specify any desired number of ranges of any suitable size, and some ranges may overlap one another or be contained in one another. The definition may also specify certain returned values and/or relative priorities for the various ranges. In a pre-processing phase, a hash table that is subsequently queried with addresses to be range-matched. The hash table may be updated at run-time. During operation, the system receives addresses (e.g., extracts addresses from monitored communication traffic) and identifies by querying the hash table, for each address, whether the address falls within any of the ranges.