Name Resolution Domain Name System. 4 Learning Objectives Provide an overview of the Domain Name System (DNS) Describe the features of DNS in Windows

Name ResolutionName Resolution

Domain Name System

4Learning ObjectivesLearning ObjectivesLearning ObjectivesLearning Objectives

Provide an overview of the Domain Name System (DNS)

Describe the features of DNS in Windows 2000 Install the DNS server Configure a DNS server Create resource records manually Configure a client to use DNS Manage, monitor, and troubleshoot DNS

4DNS OverviewDNS Overview

Host names Simple names used as aliases for IP addresses

DNS Hierarchical naming system used to resolve host name to

IP address mapping Contains resource records Primary name resolution method in Windows 2000

Host files and DNS perform the task of translating from names (host names) to IP addresses

4Host FilesHost Files

Text files that contain host name to IP address mapping

Used to perform host name to IP address resolution Precursor to the DNS system Without host name resolution, users cannot access

Internet or intranet resources via Fully Qualified Domain Names (FQDN)

4

Ways to Perform Host Name Ways to Perform Host Name to IP Address Resolutionto IP Address Resolution

4DNS StructureDNS Structure

Root-level domain Represented by a period Usually not shown on FQDN

Top-level domains Second-level domains Subdomains Individual hosts

4DNS Hierarchical StructureDNS Hierarchical Structure

4Top-level DomainsTop-level Domains

Organizational domains created by designers of the Internet to simplify the naming and logical structure of the DNS namespace

4

Second-level Domains and Second-level Domains and SubdomainsSubdomains

Second-level domains Where companies register their names with a

name registration company Gives the company authority to create

subdomains to further divide the domain namespace

4DNS ZonesDNS Zones

Zone of authority Portion of the DNS namespace that an

organization controls DNS zone

Portion of the DNS namespace that can be administered as a single unit

Each zone has a primary name server that holds the DNS zone file

4DNS ZonesDNS Zones

Primary name servers Hold a read/write copy of the zone file

Secondary name servers DNS servers configured to hold a read-only copy

of the primary name server’s DNS zone file

All networks should minimally have a primary and a secondary DNS name server

4DNS ServersDNS Servers

Can be configured as caching-only servers Hold two types of DNS zones:

Forward lookup zones (host name to IP address mapping)

Reverse lookup zones (IP address to host name mappings)

4DNS SystemDNS System

Roles available to computers in DNS system DNS servers that answer client requests DNS resolvers; clients that initiate requests

Types of requests or queries Recursive: DNS client to DNS server Iterative: DNS server to DNS server Inverse: Find a host name from a Known IP

address

4Resource RecordsResource Records

Used within the actual zone files to point to particular resources such as hosts, mail exchangers, and name servers

4Resource RecordsResource Records

continued

4Resource Records Resource Records

4Windows 2000 DNSWindows 2000 DNS

Supports incremental zone transfers Primary DNS servers send just the changes in the DNS

database to a secondary server; conserves network bandwidth

Supports dynamic DNS as defined in RFC 2136 Allows clients to register DNS information automatically

with a DNS server Supports dynamic registration of clients that do not

support DDNS through use of a service such as the Windows 2000 DHCP service

4Installing DNS ServiceInstalling DNS Service

Prerequisites Static IP address Subnet mask Default gateway Set the domain name suffix on the server

4

Setting the Domain Name Setting the Domain Name Suffix on the ServerSuffix on the Server


Use Optional Networking Components, accessible via the Advance menu in Network and Dial-up Connections



Double-click Networking Services in the Windows Optional Networking Components Wizard and select the DNS service

DNS management console is added to the Administrative Tools folder


4

Configuring Zones for Configuring Zones for Dynamic UpdatesDynamic Updates

By default, standard zones on Windows 2000 DNS servers do not support dynamic registration

4


Once configured to accept dynamic updates, all zones can allow Windows 2000 computers to create their own A records

If your network uses DHCP, you can configure DHCP servers to register PTR records for Windows 2000 clients and A and PTR records for non-Windows 2000 clients

4


4

Creating Resource Records Creating Resource Records ManuallyManually

4DNS Client ConfigurationDNS Client Configuration

For clients with static IP addresses Manually configure a Preferred DNS server and

an Alternate DNS server in TCP/IP properties DNS configuration tab for Windows 95/98 clients

For DHCP clients Configure DNS options for the scope that the

client will obtain an IP address from

4

Basic Manual DNS Configuration Basic Manual DNS Configuration for Windows 2000 Clientsfor Windows 2000 Clients

4Troubleshooting DNS Troubleshooting DNS

Use nslookup from the command prompt

Easy IPEasy IP

Dynamic Host Configuration Protocol

4Learning ObjectivesLearning ObjectivesLearning ObjectivesLearning Objectives

Describe the dynamic host configuration protocol (DHCP)

Describe the dynamic IP leasing process Configure a client to use DHCP Install the DHCP server service Configure scopes within the DHCP server

service

continued

4Learning ObjectivesLearning Objectives

Define and create scope options Authorize a DHCP server in Active

Directory Configure DHCP for integration with DNS Manage, monitor, and troubleshoot DHCP

4Overview of DHCPOverview of DHCP

Provides an easy way for network administrators to provide IP addressing information for network clients

Reduces the work associated with moving clients between subnets

DHCP server service can be used to create a pool of IP addresses known as scopes that can be dynamically assigned to clients

Options can include default gateway address, or a DNS and a WINS server address

4DHCP Lease ProcessDHCP Lease Process

Discover Offer

Request Acknowledgment

4Step 1: DHCPDiscoverStep 1: DHCPDiscover

4Step 2: DHCPOfferStep 2: DHCPOffer

4Step 3: DHCPRequestStep 3: DHCPRequest

4Step 3: DHCPRequest Step 3: DHCPRequest

4

Step 4: Step 4: DHCPAcknowledgmentDHCPAcknowledgment

4DHCP Renewal ProcessDHCP Renewal Process

4

Configuring a Windows 2000 Server Configuring a Windows 2000 Server with the DHCP Server Servicewith the DHCP Server Service

1. Configure a static IP address, subnet mask, and default gateway on the server

2. Install the DHCP server service3. Create scopes and, if needed4. Create and specify options on a server5. Authorize the DHCP server in Active Directory

4

Client Configuration for Client Configuration for DHCPDHCP

Any client that supports a standard implementation of DHCP can obtain an IP address from a Windows 2000 DHCP server

To configure Windows clients, specify that they obtain an IP address automatically by accessing the Internet Protocols (TCP/IP) properties found under Local Area Connections properties

4

Client Configuration for Client Configuration for DHCP DHCP

4

Installing the DHCP Server Installing the DHCP Server ServiceService

Minimum requirements Windows 2000 server machine configured with a static

IP address, subnet mask, and, on networks with multiple subnets or networks, a default gateway

Range of addresses that can be used to create scopes (ranges of IP addresses configured for lease to clients via DHCP)

Active Directory installed and configured to allow DHCP servers to be authorized in AD

4

Installing the DHCP Server Installing the DHCP Server Service Service

Many ways to install DHCP One of the easiest ways is to access Network

and Dial-up connections via the Start menu or right-click on My Network Places and select Properties

4Installing DHCPInstalling DHCP



Common problem on networks attempting to implement DHCP: routers do not pass broadcasts

Solutions Configure a router to pass DHCP traffic, using the

command: IP Helper-Address followed by the IP address of the DHCP server command

Place second DHCP server on same segment as the client

4

Router Blocking Router Blocking DHCPDiscover PacketsDHCPDiscover Packets

4

Configuring a DHCP Server Configuring a DHCP Server per Physical Segmentper Physical Segment

4Configuring ScopesConfiguring Scopes

4

Items in theItems in theNew Scope WizardNew Scope Wizard

Name and Description IP Address range Subnet mask Add Exclusions Lease duration Configure DHCP Options

4

Main Options Used with Main Options Used with DHCPDHCP

4DHCP and Active DirectoryDHCP and Active Directory

Create a DHCP object within Active Directory to validate DHCP servers

Requirements All DHCP servers must run Windows 2000 First DHCP server in your network must be

installed as either a domain controller or member server

4Integrating DHCP and DNSIntegrating DHCP and DNS

You can configure DHCP to create Dynamic DNS entries for clients that do not support DDNS Helps with support of legacy, non-DDNS aware

clients Windows clients can register their own A

records but they still rely on the DHCP server to create reverse lookup records

4Integrating DHCP and DNS Integrating DHCP and DNS

4Troubleshooting DHCPTroubleshooting DHCP

Misconfigured scopes or options Use ipconfig/all command to verify client

settings and information Change options within the DHCP snap-in

A stopped DHCP server service Use the net start dhcpserver command

continued

4Troubleshooting DHCPTroubleshooting DHCP

A scope that has run out of addresses Decrease length of lease for the scope Increase range of addresses in the scope Renumber entire scope with new, larger range of addresses Remove some clients from overcrowded network segment

An improperly configured network Place a DHCP server on each subnet Implement DHCP forwarding on subnets without DHCP

servers

Documents

Name Resolution Domain Name System. 4 Learning Objectives Provide an overview of the Domain Name System (DNS) Describe the features of DNS in Windows