The value of vRtrIfIpcpSecDnsAddr specifies the IP address that will
be exchanged by IPCP, if applicable on a given interface, to configure
the secondary DNS's IP address on the remote peer. The type of this
address is specified by the value of vRtrIfIpcpSecDnsAddrType.
vRtrIfIpcpSecDnsAddr can be set to non-default only when the following
rules are met for objects in vRtrIfEntry with the same indices:
- The value of vRtrIfType is set to serviceIes(3) or serviceVprn(5)
- The value of tmnxPortEncapType in tmnxPortEntry indexed using
the value of vRtrIfPortID is set to unknown (0) or nullEncap (1)
or ipcpEncap (6)