The SNMP Agent Administrative value of the subnet mask
for the private in-band access.
This value is stored in the system NVRAM.
The current operational IP Adress may be obtained by
accessing the ipAdEntNetMask entry in the ipAddrTable,
for ipAdEntIfIndex equal to the private interface
value.
If the system has no current operational IP Address,
meaning that the access is done out-of-band, then this
value takes effect immediately.
Otherwise it will take effect after a system reset