Basic Cisco Switch Question 2960X Core Switch

I have a voice vlan that is using DHCP configured on my core 2960X

My voice vlan has a few statics  ccm pub  ccm sub  unity pub  unity sub  ccx pub ccx sub presence pub
192.168.50. 12 presence sub

 I just retired a dns server and I have to
change it on the core switch that is handing out DHCP address on the 50  VLAN

How can I change the following? And where else do I have to change this setting?

ip dhcp excluded-address
ip dhcp pool Voice
 option 150 ip
 domain-name XXXXXXXXXXXXX

I want to change  to

I need the correct syntax and also my fear is that I'm running a call center
that does a lot of business so should I wait until after hours do to do this change?

the ip helper on the switch is correct but I need to get the dns server in on this scope
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To change dns-server

config t
ip dhcp pool Voice
no dns-server

You can prepare bold commands as copy - paste, so it can be done in no time. There should be no downtime at all.

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Mal OsborneAlpha GeekCommented:
No downtime, but be aware that the new DNS setting will not propagate to client machines for a while.  Worse case scenario would be 50% of the lease time.

The default on Cisco devices is one day, so if you change it one evening, the next morning  devices should pick up a new lease with the new DNS servers. Of course, the lease time may not have been left at the default.   Below is how the syntax works:

Router1#configure terminal
Router1(config)#ip dhcp pool
Router1(dhcp-config)#lease 5 12 30            

With The lease command, you are left three options: lease days, hours, minutes with hours and minutes being optional. You can specify a maximum period of 365 days, 23 hours and 59 minutes, and a minimum of 1 second. The default is 1 day.
FeenkerAuthor Commented:
Thanks for the solution it worked.
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