To spoof a customer DNS servers & NTP servers for an offline install Download and install CSR1000 IOS Virtual Router

!
ip host test.mydomain.local 10.10.10.1
ip host uc-cucmpub.mydomain.local 10.125.10.30
ip host test 10.10.10.1
!
ip domain name mydomain.local
!
ip dns server
ip dns primary mydomain.local soa ns.mydomain.local mb1.mydomain.local 
ip dns primary 2.168.192.in-addr.arpa soa 192.168.1.1 ns.mydomain.local 
!
ntp master 2
!
interface Loopback0
 ip address 10.99.5.5 255.255.255.255
!
interface Loopback1
 ip address 10.99.6.6 255.255.255.255
!
interface Loopback2
 ip address 10.99.7.7 255.255.255.255
!