VMware Workstation 4.5
A host-only network is a full-fledged network. It has a network interface associated with it (VMnet1) that is marked "up" at the time the host operating system is booted. Consequently, routing server processes that operate on the host operating system, such as routed and gated, automatically discover it and propagate information on how to reach it unless you explicitly configure them not to do so.
If either of these programs is being run only to receive routing information, the easiest solution is to run it with a -q option so that it does not supply routing information, only receives it.
If, however, they are running because they are to supply routing information, then you need to configure them so they do not advertise routes to the host-only network.
Unfortunately, the version of routed that comes with many distributions of Linux has no support for specifying that an interface should not be advertised. Consult the routed(8) manual page for your system in case you have a more contemporary version of the software.
For gated, configuration is involved. You need to explicitly exclude the VMnet1 interface from any protocol activity. If you need to run virtual machines on a host-only network on a multihomed system where gated is used and have problems doing so, please contact VMware technical support by submitting a support request at