Hi, I tried to reproduce this in our lab and was unable to.  I would open a case with EMC Support and provide a "show running-config" from a switch that the command works on and one from the switch that it's failing on.  Wish I had a better answer for you.  Erik   
Hello, I'm using the vdx6740 at VxRail ToR Switch.Firmware is 6.0.1a version.  but I has been set in the VDX best practices, it can not set "ipv6 mld snooping querier enable"configuration of Vlan1. I can not be understand.  Error is following. > Error(s): > vlan 1: %% Error: Configuration not allowed as vlan is a private-vlan  I have Other vdx6740 switches ,it can set ipv6 snooping querier enable settings for same firmware. What is the problem?  --running-config-- interface Vlan 1  ip igmp snooping enable  ip igmp snooping querier enable  ipv6 mld snooping enable  
Can'not config ipv6 mld snooping querier at VDX6740 (VxRail B series Switch 
config)