Hello Ksohan4730,
I see in our newer ISR routers with IOS release 12.4 or 12.4T that the global command:
no ip dhcp use vrf connected
is present by default in the configuration.
What is to be noted is that the command is not present in the command reference in IP addressing services
http://www.cisco.com/en/US/docs/ios/ipaddr/command/reference/iad_dhc2.html#wp1013858
We never had the need to change the default settings also on routers acting as DHCP servers that we use in some cases.
The command looks like to be related to VRFs, virtual routing and forwarding that are defined for VRF lite or MPLS L3 VPN.
the possible effect is to consider the interfaces mapped in VRFs for DHCP commands (server activity or DHCP relaying function).
By default when an interface is associated to a VRF it is removed from the list of connected interfaces that are in the normal routing table (Global routing table).
so the command no ip dhcp use vrf connected should leave interfaces in VRF not considered by DHCP activity.
Hope to help
Giuseppe
