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Name ResolutionName Resolution

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NetBIOS name resolutionNetBIOS name resolution

NetBIOS name = computer name.

Microsoft commands use NetBIOS names.

Example: Net View \\ computer_name

NetBIOS names must be resolved to their TCP/IP

addresses before a connection can be established.

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NBTStat utilityNBTStat utility

nbtstat -n Lists all NetBIOS names registered in cache.

nbtstat -R Clears name cache and reloads any names

pre-loaded in LMHOSTS file.

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B-node (Broadcast node)B-node (Broadcast node)

NetBIOS names are resolved through broadcasts.

Who is

Computer 2?

Computer 1 Computer 2

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B-node (Broadcast node) (cont.)B-node (Broadcast node) (cont.)

NetBIOS names are resolved through broadcasts.

100.100.1.2

is Computer 2.

Computer 1 Computer 2

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P-node (Peer-to-peer node)P-node (Peer-to-peer node)

NetBIOS name is resolved through directed datagrams to NetBIOS

Name Server.

To: NBNS

Who is Computer 2?

Computer 1

Computer 2

NBNS

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P-node (Peer-to-peer node) (cont.)P-node (Peer-to-peer node) (cont.)

NetBIOS name is resolved through directed datagrams to NetBIOS

Name Server.

To: NBNS

Who is Computer 2?

To: Computer 1

100.100.1.2 is Computer 2

Computer 1

Computer 2

NBNS

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P-node (Peer-to-peer node) (cont.)P-node (Peer-to-peer node) (cont.)

NetBIOS name is resolved through directed datagrams

to NetBIOS Name Server.

To: NBNS

Who is Computer 2?

To: Computer 1

100.100.1.2 is Computer 2

Computer 1

Computer 2

NBNS

Sends packet to Computer 2

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M-node vs. H-nodeM-node vs. H-node

Who isComputer 2?

To: NBNSWho is Computer 2?

If no response

Who isComputer 2?

To: NBNSWho is Computer 2?

M-node H-node

1.

2.

If no response

1.

2.

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NetBIOS name resolution and NetBIOS name resolution and LMHOSTSLMHOSTS

LMHOSTS file - Maps IP addresses to NetBIOS names.

Maintained in the winnt-root\system32\drivers\etc

directory.

#PRE - Pre-loads mapping into the NetBIOS name cache.

#DOM: Domain_name - Indicates that the machine listed is a domain

controller for that domain.

Example: 100.100.1.2 Server1 #PRE #DOM: Domain2

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Troubleshooting LMHOSTS filesTroubleshooting LMHOSTS files

Computer name misspelled. Incorrect IP address. LMHOSTS filename is incorrect (for example, LMHOSTS.TXT). #PRE and #DOM tags missing or in lower case. Registry on remote machine with LMHOSTS file not configured

correctly. Incorrect UNC path in #INCLUDE statements. Duplicate entries for the same computer or IP address in LMHOSTS

file.

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Microsoft host name resolutionMicrosoft host name resolution

• Local host• HOSTS file• Domain Name System (DNS)• NetBIOS name cache• WINS server• Broadcasts• LMHOSTS file

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HOSTS file guidelinesHOSTS file guidelines

Must be in \winnt_root\system32\drivers\etc path Each entry 255 characters Multiple names can be configured per IP address Not case-sensitive No special tags (#PRE, #DOM, #INCLUDE) supported Include entry for localhost File parsed from top to bottom Precede any comments with a semicolon

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Troubleshooting HOSTS filesTroubleshooting HOSTS files

Misspelled computer or host names Incorrect IP addresses HOSTS filename misspelled or not in the correct

format Multiple entries for the same name or address in

HOSTS file

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The DNS hierarchyThe DNS hierarchy

.com .gov .edu

zdeducation.com microsoft.com whitehouse.gov

dev.microsoft.com

berkeley.edu

research.berkeley.edu

ntserver.zdeducation.com

ntworkstation.zdeducation.com

labcomputer.research.berkeley.edu

<Root>

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The DNS Server serviceThe DNS Server service

What is the address

for server.company.com?

DNS client Windows NT server

running DNS Server

Server.company.com

is 137.105.21.5.