DHCP assigning IP addresses out of sequence

[ckeyy]

I’m using the core switch as the DHCP server for 5 VLANs, with the first 10 IP addresses (.1 to .10) excluded. The lease time is set to 24 hours. However, when I check the DHCP client list or use the show ip dhcp binding command, it shows that IP addresses are being assigned out of sequence like it starts from 34 instead of 11 and like 34, 48, 50, and so on, and addresses are leased up to .254 or the current index. As a result, we’re experiencing IP exhaustion even though the full 254 addresses are not actually being leased out or used, as confirmed by the show ip dhcp pool command and manually checking it. What could be the possible solution for this? By the way, the setup has access switches connected to the core.

[MHM Cisco World]

the DHCP use free IP it can in order or out of order. 
in your case you can face exhausted dhcp, so best solution is reduce the lease to be 30 min 

MHM 

[ckeyy]

But 30 min is not the best practice, right? Because the recommended lease is 24 hours or 1 day

[MHM Cisco World]

if the user is not connect anymore this make DHCP reserve it IP for 24 and hence the Pool of IP is exhausted by these user. 

MHM

[ckeyy]

Do you have document for this "the DHCP use free IP it can in order or out of order." from cisco?