2.0

Table Of Contents
VMware, Inc. 249
Chapter 11 Configuring a Virtual Network
The Host Computer and the NAT Network
ThehostcomputerhasahostvirtualadapterontheNATnetwork(identicaltothehost
virtualadapteronthehostonlynetwork).Thisadapterallowsthehostandthevirtual
machinestocommunicatewitheachotherforsuchpurposesasfilesharing.TheNAT
neverforwardstrafficfromthehost
virtualadapter.
DHCP on the NAT Network
Tomakenetworkingconfigurationeasy,aDHCPserverisautomaticallyinstalledwhen
youinstallVMwareServer.VirtualmachinesrunningonthenetworkwiththeNAT
devicecandynamicallyobtaintheirIPaddressesbysendingoutDHCPrequests.The
DHCPserverontheNATnetwork,whichisalsousedinhostonly
networking
configurations,dynamicallyallocatesIPaddressesintherangeof<net>.128through
<net>.254,where<net>isthenetworknumberassignedtoyourNATnetwork.
VMware ServeralwaysusesaClassCaddressforNATnetworks.IPaddresses<net>.3
through<net>.127canbeusedforstaticIPaddresses.IPaddress<net>.1is
reservedfor
thehostadapterand<net>.2isreservedfortheNATdevice.
InadditiontotheIPaddress,theDHCPserverontheNATnetworkalsosendsout
additionalconfigurationinformationthatenablesthevirtualmachinetooperate
automatically.ThisinformationincludesthedefaultgatewayandtheDNSserver.In
the
DHCPresponse,theNATdeviceinstructsthevirtualmachinetousetheIPaddress
<net>.2asthedefaultgatewayandDNSserver.ThiscausesallIPpacketsdestinedfor
theexternalnetworkandDNSrequeststobeforwardedtotheNATdevice.
DNS on the NAT Network
TheNATdeviceactsasaDNSserverforthevirtualmachinesontheNATnetwork.
Actually,theNATdeviceisaDNSproxyandmerelyforwardsDNSrequestsfromthe
virtualmachinestoaDNSserverthatisknownbythehost.Responsescomebacktothe
NATdevice,which
thenforwardsthemtothevirtualmachines.
IftheygettheirconfigurationinformationfromDHCP,thevirtualmachinesonthe
NATnetworkautomaticallyusetheNATdeviceastheDNSserver.However,the
virtualmachinescanbestaticallyconfiguredtouseanotherDNSserver.
ThevirtualmachinesintheprivateNAT
networkarenot,themselves,accessibleusing
DNS.IfyouwantthevirtualmachinesrunningontheNATnetworktoaccesseach
otherbyDNSnames,youmustsetupaprivateDNSserverconnectedtotheNAT
network.