We have a forest with several sub domains connected through MPLS. When running in the Top level domain you are not able to browse for shares in the sub domains. We have enabled NetBios over TCP/IP on the file servers in the sub domain but we are still unable to browse for share. If we map a drive direct using the FQDN it works without any issue.
As mkleij mentioned , broadcasts are not supported across the subnets , so you can use LMHOST file in order perform name resolution across the subnets.
Prior to using name resolution techniques i would first test if the IPaddress resoluution is happening, and then move to name resolution [wins / DNS ]
If I remember correctly netbios names are not resolved cross subnets by default. You need to implement something like a wins server to make that possible. Another possibility would be using DNS (single label DNS names). Single label DNS is to proposed successor of netbios.
As mkleij mentioned , broadcasts are not supported across the subnets , so you can use LMHOST file in order perform name resolution across the subnets.
Prior to using name resolution techniques i would first test if the IPaddress resoluution is happening, and then move to name resolution [wins / DNS ]