Workstation User’s Manual
318 VMware, Inc.
DNS on the NAT Network
TheNATdeviceactsasaDNSserverforthevirtualmachinesontheNATnetwork.
The NATdeviceisaDNSproxyandforwardsDNSrequestsfromthevirtualmachines
toaDNSserverthatthehostknows.ResponsesreturntotheNATdevice,whichthen
forwardsthemtothevirtualmac
hines.
IftheygettheirconfigurationinformationfromDHCP,thevirtualmachinesonthe
NATnetworkautomaticallyusetheNATdeviceastheDNSserver.However,the
virtualmachinescanbestaticallyconfiguredtouseanotherDNSserver.
ThevirtualmachinesintheprivateNATnetworkarenotaccessiblethroughDNS.To
hav
ethevirtualmach
inesrunningontheNATnetworkaccesseachotherbyDNS
names,youmustsetupaprivateDNSserverconnectedtotheNATnetwork.
External Access from the NAT Network
AvirtualmachineontheNATnetworkcanuseanyprotocolusingTCPorUDPaslong
asthevirtualmachineinitiatesthenetworkconnection.Thisistrueformostclient
applicationssuchasWebbrowsing,Telnet,passive‐modeFTP ,anddownloading
streamingvideo.AdditionalprotocolsupportisbuiltintotheNA
TdevicetoallowFTP
andICMPecho(ping)toworktransparentlythroughtheNAT.
Ontheexternalnetworktowhichthehostisconnected,anyvirtualmachineonthe
NATnetworkappearstobethehostitself,becauseitsnetworktrafficusesthehost’s
IP address.Thevirtualmachinecansendandre
ceivedatausingTCP/IPtoanymachine
thatisaccessiblefromthehost.
Beforeanycommunicationcanoccur,theNATdevicemustsetupamapbetweenthe
virtualmachine’saddressontheprivateNATnetworkandthehost’snetworkaddress
ontheexternalnetwork.
Whenavirtualmachineinitiatesanetw
orkconnectionwithanothernetworkresource,
thisma
piscreatedautomatically.Theoperationistransparenttotheuserofthevirtual
machineontheNATnetwork.Noadditionalworkneedstobedone.
NetworkconnectionsthatareinitiatedfromoutsidetheNATnetworktoavirtual
machineontheNATne
tworkarenottransparen
t.Whenamachineontheexternal
networkattemptstoinitiateaconnectionwithavirtualmachineontheNATnetwork,
itcannotreachthevirtualmachinebecausetheNATdevicedoesnotforwardthe
request.
However,youcanconfigureportforwardingmanuallyontheNATdevicesothat
netw
orktrafficdestinedforacertainportcanstillbeforwardedautomaticallytoa
virtualmachineontheNATnetwork.See“AdvancedNATConfiguration”onpage 319.
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