When ordering IP addresses, after selecting the IP range a box appears on the right hand side of the screen showing the timer going down. 

The reason for this is to secure your selection from other users. When you select the range, it is then marked as reserved and is no longer published when other users search for IPs. If you did not buy the range in 10 minutes, it is then marked as unreserved and again suggested to other users as an option to buy. 

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