There are four common NetBIOS-related issues:

- NetBIOS node type misconfiguration
- NetBIOS workgroup mismatch
- NetBIOS scope mismatch
- Duplicate NetBIOS names
These issues are usually a result of misconfiguration by a user or
network engineer. Note that several of these problems can be caused by DHCP
server misconfiguration.
One of the most common misconfigurations on a
small NetBIOS network is the NetBIOS node type. There are four possible
settings for the NetBIOS node type:

- B-node (Broadcast node)
- P-node (Peer-to-peer node)
- M-node (Mixed node)
- H-node (Hybrid node)
Configuring the NetBIOS node type as peer-to-peer in a network that
does not have a NetBIOS name server stops the network from functioning.
Conversely, using broadcast-mode in a routed network stops the hosts from
accessing resources across the router.
The NetBIOS node type is usually
set using a DHCP server. DHCP can be used to set a number of optional settings
on the client. The settings are referred to as DHCP options. DHCP options
commonly used are shown in Figure
. Because Cisco
routers can be configured as DHCP servers, NetBIOS DHCP options need to be
taken into account. Use the commands netbios-name-server
name-server-address and netbios-node-type type
from DHCP-configuration mode to implement NetBIOS DHCP options
from a Cisco router-based DHCP server.
DHCP options 44 and 46 are
commonly used in NetBIOS networks with NetBIOS name servers. The NetBIOS node
type can also be set manually on Windows hosts. The registry of the Windows
machine must be edited to do this.
When two NetBIOS computers have
different values defined for the workgroup name, these computers are unable to
communicate. The workgroup name is usually configured during the initial
installation of the computer operating system or when networking is being added
to the computer. The workgroup name is not case-sensitive.
The NetBIOS Scope ID is a left-over piece of NetBIOS technology rarely used
in modern networking. A NetBIOS Scope is a group of computers that can only
communicate with each other. Because the NetBIOS Scope ID is blank by default,
a single computer misconfigured with a NetBIOS Scope ID is not able to
communicate with other hosts on the network.
Because this is a setting
that is not often used, it can be difficult to troubleshoot. Note that like the
NetBIOS node type, the NetBIOS Scope ID can also be controlled centrally from
the DHCP server, using DHCP option 47. Unlike the node type however, the Scope
ID can also be easily altered on the local machine through the network
interface GUI.
When duplicate NetBIOS names exist in a network, the
duplicate hosts are unable to connect to the network until they are configured
with a unique NetBIOS name. Duplicate NetBIOS names occur most often when there
is no structure to the naming scheme in a NetBIOS network.
The host name
can be set using DHCP option 12. This option is intended for use when using
DHCP reservations (where an IP address is specifically reserved for a given MAC
address), as it allows for full host-specific network information to be
controlled from a single administrative interface. Using DHCP option 12 with
dynamic DHCP clients would cause significant problems on the network.