The LMHOSTS is a static file that assists with remote NetBIOS name
resolution on computers. It contains NetBIOS name-to-IP address mappings. This
document describes the role of the LMHOSTS file in a Cisco Intelligent Contact
Management (ICM) environment.
A. The LMHOSTS file maps NetBIOS names to IP addresses. Cisco ICM servers
require Microsoft NetBIOS over TCP/IP protocol to communicate with each other.
A NetBIOS session is established between two NetBIOS names. A session setup
involves the following phases:
NetBIOS name resolution using Windows Internet Name Service (WINS)
server, or the static LMHOSTS file.
NetBIOS name query request -->
<-- NetBIOS name query response
TCP connection is established:
A NetBIOS session is set up over that connection:
NetBIOS session setup request -->
<-- NetBIOS session setup response
In most instances, it is a Named Pipes connection such as mapping a
remote drive, establishing a SQL Server connection.
The LMHOSTS file is different from the HOSTS file, as a HOSTS file
contains IP name-to IP address mappings. The HOSTS file includes addresses for
IP routers, automatic call distributors (ACD), voice response units (VRU),
application gateway servers, public, public high-priority, private, and private
high-priority addresses. Cisco ICM servers resolve IP hostnames through a
Domain Name Service (DNS) server or the static HOSTS file by
gethostbyname Application Program Interface (API) so they can
bind the right TCP/IP socket port to the right address (interface), and allow a
server to connect to other hosts through the correct addresses on the
HOSTS name resolution is equivalent to what the DNS server does. It
includes all IP addresses used by Cisco ICM servers, and everything else they
connect to. LMHOSTS name resolution is equivalent to what the WINS server does.
It includes only those addresses associated with the public address of each ICM
server. For example, Network Neighborhood -- only servers and
addresses that appear in Network Neighborhood are in the
For example: CallRouterA communicates with CallRouterB over private and
private high-priority addresses. When the MDS processes start, they run a
gethostbyname lookup to request addresses to use for its own
sockets, and the IP address of the peer server on the private network. The
CCAgent processes on the CallRouters bind the sockets to the visible, and
visible high-priority address, so the Peripheral Gateway PGAgent process can
connect to these routers. CCAgent performs a gethostbyname
lookup to know which addresses to bind its ports to. PGAgent also performs a
HOSTS file lookup to know how to connect to the visible and visible
high-priority addresses of the CallRouter.
When running a net use command from the PG
to the CallRouter, it performs a LMHOSTS lookup, and only includes the one
address associated with the CallRouter hostname.
ICM uses a HOSTS and LMHOSTS file as an alternative to a DNS and WINS
server. Since ICM servers use a static set of addresses instead of the Dynamic
Host Configuration Protocol (DHCP) , the maintenance of the HOSTS and LMHOSTS
file is fairly easy to manage. Use of the HOSTS and LMHOSTS eliminates the
requirement of a functional DNS or WINS server. ICM servers do not rely on the
fact that WINS or DNS server is available and functional. Many times ICM
servers are in a separate domain, and are physically (or logically) on separate
data networks from other customer servers.
The HOSTS and LMHOSTS file are both located in the
\winnt\system32\drivers\etc directory on every
It is recommended that you only modify the HOSTS and LMHOSTS files on
the Logger server. As the Logger server is the Primary Domain Controller (PDC)
and all the systems connect to it, it should always be available. Keep the
master HOSTS and LMHOSTS files in this centrally managed and controlled
location, and use
to propagate the changed HOSTS and LMHOSTS file to all ICM servers.