MCSE - Troytech Admin Network Infrastructure [70-216].pdf

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Microsoft Word - Troytech 70-216 W2K Managing & Supporting .doc
Implementing, Managing and Supporting Windows 2000 Network Infrastructure Concepts
DNS in a Windows 2000 Network Infrastructure
DNS Overview
DNS is the name service for Internet addresses used to translate friendly domain names to
numeric IP addresses. Microsoft's web page, http://www.microsoft.com translates to
207.46.130.149. A host computer queries the name of a computer and a domain name server
cross-references the name to an IP address.
Windows 2000 clients use DNS for name resolution and locating domain controllers for logon. In
the DNS, the clients are resolvers and the servers are name servers. DNS uses three components:
resolvers, name servers, and the domain name space. A resolver sends queries to a name server.
The name server returns the requested information, a pointer to another name server, or a failure
message, if the request cannot be satisfied.
Resolvers
Resolvers pass name requests between applications and name servers. The name request contains
a query, such as the IP address of a Web site. The resolver can be built into the application or may
be running on the host computer as a library routine.
Name Servers
A name server contains address information about other computers on tile network. Name servers
are grouped into domains. Access to each computer in a given group is controlled by the same
server. If the name server is not able to resolve the request, it can forward the request to another
name server.
Root-Level Domains
Domains define levels of authority in a hierarchical structure. The top of the hierarchy is called
the root domain. References to the root domain are expressed by a period (.).
Top-Level Domains
Top-Level Domains include the following:
arpa
Reverse
DNS
com
Commercial organizations
edu
Educational institutions and universities
gov
Nonmilitary government organizations
mil
Military government organizations )
net
Networks (the backbone of the Internet
num
Phone numbers
org
Non-profit organizations
xx
Two-letter country code
Second-Level Domains
Second-level domains contain hosts and other domains, called subdomains.
Host Names
The domain name is used with the host name to create a fully qualified domain name (FQDN).
The FQDN is the host name followed by a period (.), followed by the domain name.
Zones
A zone is the administrative unit for DNS. It is a subtree of the DNS database that is administered
as a single, separate entity. It can consist of a single domain or a domain with subdomains. The
lower-level subdomains of a zone can also be split into separate zones.
Name Server Roles
The minimum number of DNS servers for each zone is two - a primary and a secondary. The
existence of both servers provides for database redundancy and a level of fault tolerance.
Primary Name Servers
Primary name servers get the data for their zones from the local DNS database files. When a
change is made to the zone data the change must be made on the primary DNS server so that the
new information is entered in the local zone file.
Secondary Name Servers
Secondary name servers get their zone data file from the primary DNS server that is authoritative
for that zone. Zone transfer is the process of the primary DNS server sending a copy of the zone
file to the secondary DNS server. Secondary servers allow for redundancy, quicker access for
remote locations, and load balancing. Primary or secondary designation is defined at a zone level
because information for each zone is stored in separate flies. A particular name server may be a
primary name server for certain zones and a secondary name server for other zones.
Caching-Only Servers
Caching-only servers are DNS name servers that perform queries, cache the answers, and return
the results. No zone data is kept locally. They contain only information that they have cached
while resolving queries. Less traffic is generated between servers because the server is not doing
a zone transfer. Caching-only servers can be used if you have a slow connection between sites.
DHCP in a Windows 2000 Network Infrastructure
DHCP Overview
DHCP centralizes and manages the allocation of TCP/IP configuration information by
automatically assigning IP addresses to computers configured to use DHCP. Each
time a DHCP client starts, it requests IP address information from a DHCP server, including the
IP address, the subnet mask, and optional values. The optional values may include a default
gateway address, Domain Name System (DNS) address, and Windows Internet Name Service
(WINS) server address. When a DHCP server receives a request, it selects IP addressing
information from a pool of addresses defined in its database and offers it to the DHCP client. If
the client accepts the offer, the IP addressing information is leased to the client for a specified
period of time. If there is no available IP addressing information in the pool to lease to a client,
the client cannot initialize TCP/IP.
Windows 2000-based clients can automatically configure an IP address and subnet mask if a
DHCP server is unavailable at system start time through Automatic Private IP Addressing
(APIPA). The Windows 2000 DHCP client service goes through the following process to
autoconfigure the client:
· The DHCP client tries to locate a DHCP server and obtain an address.
· If a DHCP server does not respond or cannot be found, the DHCP client auto-configures its
IP address and subnet mask using a selected address from reserved Class B network,
169.254.0.0, with the subnet mask 255.255.0.0.
· The DHCP client then tests for address conflicts. If a conflict is found, the client will retry
autoconfiguration for up to 10 addresses.
· Once the DHCP client succeeds in selecting an address, it configures its net-
work interface with the IP address. The client continues to check for a I)HCP
server every 5 minutes. If a DHCP server is later found, the client will use an
address offered by the DHCP server.
Installing and Configuring a DHCP Server
The DIICP Server service must be running to communicate with DHCP clients. Once installed,
several options must be configured:
· Install the Microsoft DHCP Server service.
· Authorize the DHCP server.
· Configure a scope or pool of valid IP addresses before a DHCP server can lease IP
addresses to DHCP clients.
· Configure Global scope and client scope options for a particular I)HCP client.
You should manually configure the DHCP server computer to use a static IP address. The DHCP
server cannot be a DHCP client. It must have a static IP address, subnet mask, and default
gateway address.
Installing DHCP Server Services
1. Clicking Start, Settings, and Control Panel.
2. Double-click Add/Remove Programs, then click Add/Remove Windows Components.
3. Click Networking Services.
4. Click Details.
5. Under Subcomponents of Networking Services, select Dynamic Host Configuration Protocol
(DHCP), click OK, then click Next.
6. Type the full path to the Windows 2000 distribution files and click Continue. Required files
will be copied to your hard disk.
7. Click Finish to close the Windows Components Wizard.
Authorizing a DHCP Server
An unauthorized DHCP server may either lease incorrect IP addresses to clients or negatively
acknowledging DHCP clients. Clients that obtain a configuration lease from the unauthorized
server can fail to locate valid domain controllers, preventing clients from successfully logging on
to the network. For the directory authorization process to work properly, it is necessary that the
first DHCP server introduced on to your network participate in the Active Directory service. The
server must be installed as either a domain controller or a member server. The authorization
process for DHCP server computers in Active Directory depends on the installed role of the
server on your network; domain controller, member server, or stand-alone server. If Active Di-
rectory is deployed, all computers operating as DHCP servers must be either domain controllers
or domain member servers.
Authorizing as a DHCP Server in Active Directory
You must log on to the network using an account that has membership in the Enterprise
Administrators group that allows you Full control rights to the NetServices container object as it
is stored in the Enterprise Root of the Active Directory service.
1. Install the DHCP service on this computer (if necessary).
2. Click Start, Programs, Administrative Tools, then click DHCP.
3. On the Action menu, click Manage Authorized Servers.
4. ClickAuthorize.
5. When prompted, type the name or IP address of the DHCP server to be authorized, then click
OK.
Creating a DHCP Scope
A scope is a pool of valid IP addresses available for lease to DHCP clients. It must be created
before a DHCP server can lease an address to DHCP clients. One scope for every DHCP server
must be created. Static IP addresses must be excluded from the scope. To centralize
administration and to assign IP addresses specific to a subnet, create multiple scopes on a DHCP
server. Only one scope can be assigned to a specific subnet. Because DHCP servers do not share
scope information, you must ensure that the same IP addresses do not exist in more than one
scope to prevent duplicate IP addressing.
Creating a New Scope
1. Click Start, Programs, Administrative Tools, then click DHCP.
2. Click the applicable DHCP server.
3. On the Action menu, click New Scope.
4. Follow the instructions in the New Scope Wizard. After creating a new scope, you need to
activate the scope for use or for assigning scope options.
Configuring DHCP for DNS Integration
A Windows 2000 DHCP server can register with a DNS server and update pointer (PTR) and
address (A) resource records (RRs) on behalf of its DHCP-enabled clients using the Dynamic
DNS update protocol. DHCP option code (Option Code 81) enables the return of a client's FQDN
to the DHCP server. The DHCP server can dynamically update DNS to modify an individual
computer's RRs with a DNS server using the dynamic update protocol.
Dynamic Updates for Non-Supported Dynamic DNS Updates
1. Click Start, Programs, Administrative Tools, then click DNS.
2. Click the applicable zone.
3. On the Action menu, click Properties.
4. In the DNS Property tab, select Enable Updates For DNS Clients That Do Not Support
Dynamic Update.
5. Select Only Secure Updates If Your Zone Type Is Active Directory-Integrated.
Troubleshooting DHCP Clients
Most DHCP-related problems start as a failed IP configuration at a client. It' the client is not the
clause, check the system event log and DHCP server audit logs. These logs contain the source of
the service failure or shutdown. Use the IPConfig TCP/IP utility to get information about tile
configured TCP/IP parameters on local or remote computers on the network.
DIICP Errors
Invalid IP address configuration
Possible network hardware failure or the DHCP server is unavailable. Verify the client computer
has a valid, functioning network connection.
Autoconfiguration problems on the current network
Use the ping command to test connectivity. Manually renew the client lease. If the client
hardware appears to be functioning properly, ping the DHCP server from another computer on
the same network. Release or renew the client's address lease.
Missing configuration details
The IP address of the DHCP server was changed
DHCP server is not configured to distribute options or the client does not support the options
distributed by the server. Verify that the most commonly used and supported options have been
configured at either the server, scope, client, or class level of option assignment. Check the
DHCP option settings. Check to see if the DHCP server is configured with an incorrect DHCP
router option (Option Code 3).
Make sure that the DHCP server IP address tells in the same network range as the scope it is
servicing.
DHCP clients un able
to receive an address
from the server,
A DHCP server can provide IP addresses to client computers oil remote
multiple subnets only if the router that separates them can act as a DHCP
relay agent. Configure a BOOTP/DHCP relay agent on the client subnet.
The relay agent can be located on the router itself or on a Windows 2000
Server computer running the DHP Relay service component.
Multiple DHCP
servers exist on the
same LAN.
Do not configure multiple DHCP servers on the same LAN with
overlapping scopes. The DHCP service, when running under Small
Business Server, automatically stops when it detects another DHCP server
on the LAN.
Troubleshooting DHCP Servers
Make sure that the DHCP services are running by opening the DHCP service console to view
service status, or by opening Services and Applications under Computer Manager.
DHCP Relay Agent
A relay agent is a program that relays DHCP/BOOTP messages between clients and servers on
different subnets. For each IP network segment that contains DHCP clients, either a DHCP server
or a computer acting as a DHCP relay agent is required.

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