Random replacement algorithm replaces a random page in memory. This eliminates the overhead cost of tracking page references. Usually it fares better than FIFO, and for looping memory references it is better than LRU, although generally LRU performs better in practice.
Belady's Anomaly
Random algorithm suffers from Belady's Anomaly because since it selects pages randomly, it might replace pages exactly like FIFO which in turn suffers from Belady's Anomaly.
Example
