1 Chapter 6 Resolving Network Host Names

1 Chapter 6 Resolving Network Host Names

|1|Chapter 6 Resolving Network Host Names

Chapter 6, Lesson 1

TCP/IP Naming Schemes

|2|1.Lesson 1 Topic

A.IP naming schemes

|3|B.Lesson objective

1.To explain the different naming schemes used by hosts

2.Microsoft Windows 2000 Naming Schemes

|4|A.Name resolution

1.Domain Name System (DNS)

2.Windows Internet Name Service (WINS)


4.HOSTS file

5.LMHOSTS file

B.Naming scheme affects the way the host is referenced.

|5|1.Three methods for NET USE command x


2.NetBIOS name or host name must be resolved to an IP address before Address Resolution Protocol (ARP) can resolve an IP address to a hardware address.

3.Summarize Lesson. Check for Questions.

Chapter 6, Lesson 2

Host Names

|6|1.Lesson 2 Topic

A.How host name resolution works

|7|B.Lesson objectives

1.To explain how the HOSTS file resolves a host name to an IP address

2.To explain how a host name is resolved to an IP address using a DNS server and Microsoft-supported methods

2.Understanding Host Names

|8|A.Host names

1.An alias to reference an IP address

2.Up to 255 characters

3.Alphabetic and numeric characters can be used.

4.Uses “–” and “.” characters

5.Multiple names can be assigned to one host.

6.For Windows clients, the host name does not have to match the computer name.

|9|B.Windows Sockets (WinSock) Applications

1.Uses one of two values

a.IP address
b.Host name

2.Host name must be resolved to an IP address.

3.Host name forms

a.Nicknames are aliases.
b.Domain names are structured names that follow Internet conventions.

|10|3.Purpose of Host Names

A.Simplifies the way a user references other TCP/IP hosts

1.Easier to remember than IP addresses

2.Can be used as an alias for utilities such as PING

3.By default, a computer’s name is also its host name.

B.Corresponds to an IP address

1.Stored in HOSTS file or database in DNS server

2.Windows clients can translate between host names and NetBIOS names.

a.WINS server

|11|4.Host Name Resolution

A.Mapping host names to IP addresses

1.NetBIOS name resolution

a.Session level interface
b.Session management/data transport protocol
c.NetBIOS uses name registration, name release, and name discovery
(1)Name cache
(2)Name server
|13|(3)Local broadcasts
(4)LMHOSTS file
(5)HOSTS file

|14|B.NetBIOS name resolution

1.A NetBIOS name is a unique 16-byte address.

2.Resolves a NetBIOS name to an IP address

3.A unique NetBIOS name is registered based on the computer name.

a.Use local broadcast: NetBIOS-over-TCP/IP mode
b.Each computer is responsible for challenging a duplicate name.

|15|C.Resolving names with a HOSTS file

1.A user calls a Microsoft Windows Sockets (WinSock)-based application referencing a host name.

2.Window 2000 checks the host name against the local host.

a.If the names are different, the HOSTS file is parsed.

b.If names are the same, then the HOSTS file is resolved to an IP address.

c.If the name cannot be resolved by a NetBIOS name server or a LMHOSTS file, user receives error message.

3.An attempt is made to resolve the IP address to a hardware address.

a.On a local network, ARP uses a cache or a broadcast.

b.If destination host is remote, then the request is routed.

D.Resolving names with a DNS server

1.A DNS server is a centralized online database that resolves host names to IP addresses.

a.Windows 2000 can be a DNS client.

b.Windows 2000 Server can provide DNS services.

|16|2.Resolution process

a.A user types a fully qualified domain name (FQDN) or a host name.

(1)The HOSTS file resolution procedure is used.
(2)The request is sent to a DNS server.
(3)If the DNS server does not respond, the request is repeated at intervals of 1, 2, 2, and 4 seconds.
(4)If there is no response from the DNS server, an error is reported to the user.

b.When the host name is resolved, ARP obtains the hardware address.

|17|E.Microsoft methods of resolving host names

1.Order of resolution

a.A host name is referenced.

b.The host name is compared with the local host name.

c.If the names do not match, the HOSTS file is parsed.

d.If host name is not found, a request is sent to a DNS server.

e.If DNS server does not respond

(1)Additional attempts are made at 1, 2, 2, and 4 seconds.
(2)An error message is displayed.

f.If DNS cannot resolve host name, the source checks with NetBIOS name cache.

g.If the DNS cache doesn’t have the name, the source contacts a NetBIOS name server.

h.If host name is not resolved by NetBIOS name server, the host generates three broadcast messages on local network.

i.If the host name is not resolved using broadcasts, LMHOSTS file is parsed.

j.If name not resolved, then only way to communicate is with IP address.

5.Summarize Lesson. Check for Questions.

Chapter 6, Lesson 3

The HOSTS File

|18|1.Lesson 3 Topic

A.The HOSTS file

|19|B.Lesson objective

1.To configure and use the HOSTS file

2.Understanding the HOSTS File

|20|A.Maps host names to IP addresses

1.Static file

2.Compatible with UNIX HOSTS file

3.Used by PING and other TCP/IP applications

4.Can resolve NetBIOS names (Microsoft TCP/IP-32-specific)

a.Must be a HOSTS file on each computer if this is the only name resolution method being used

b.Localhost resolves to

c.HOSTS file is parsed when host name is referenced. Names are read in linear fashion.

5.Best usage

a.Commonly used names should be near the beginning of the file.

b.The file can be edited with any text editor.

6.Located in the \%systemroot%\System32\Drivers\Etc directory

a.Entries are limited to 255 alphanumeric characters.

b.HOSTS files are not case-sensitive.

|21|B.Within HOSTS file

1.Multiple host names can be assigned to the same IP address.



c.Domain name

2.Entries can be case-sensitive.

a.Case-sensitive for UNIX

b.Windows 2000 and Windows 2000–based computers are not case-sensitive.

|22|3.Advantages of Using a HOSTS File

A.HOSTS files are customizable.

1.Each user can create easy-to-remember nicknames for frequently accessed resources.

B.Easier to maintain for small networks

1.Individual maintenance of the HOSTS file does not scale well to storing large numbers of FQDN mappings.

4.Practice: Working with the HOSTS File and DNS

5.Summarize Lesson. Check for Questions.

Outline, Chapter 61

Microsoft Windows 2000 Network Infrastructure Administration