Chapter 7: Domain Name System
IST 363 Network Administration
Integrated Science and Technology
Marshall University
IST363: Network Administration
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Outline
Describe the functions of the Domain Name System Install DNS Explain the function and types of DNS zones Configure a caching-only server to speed host name resolution Discuss the integration of Active Directory and DNS, including Dynamic DNS Configure and manage a DNS serverIST363: Network Administration
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Features of the DNS Service
The most common method used to resolve host names to IP addresses Essential function for Active Directory service, large networks, and for computers accessing the internet;-Windows 2000/XP client computers use DNS to find domain controllers, which require clients to log on to Active Directory (AD);
-The DNS service on Windows Server 2003 has the ability to store DNS information in AD;
IST363: Network Administration
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DNS Implementations
DNS exists in various implementations; BIND (Berkeley Internet Name Domain) is the de facto standard for DNS implementation on UNIX and Linux systems- The Internet Software Consortium (ISC) is responsible for the maintenance and development of BIND;
Microsoft offers three versions of DNS: the Windows NT4 DNS service, the Windows 2000 DNS service, and the Windows 2003 DNS service Only Windows 2000 and 2003 supports Service Resource Records (SRV records); SRV records are required for Active Directory;IST363: Network Administration
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Installing DNS
Windows Server 2003 has the ability to act as a DNS server; Most organizations using Active Directory use Windows for their DNS server If no DNS server has been configured for the domain, then the Active Directory Installation wizard asks whether it should install DNS Provides a easy way to implement DNS in a small organization with a single server; In larger organizations, DNS is installed on multiple servers, in this case, DNS must be added to each server individually;IST363: Network Administration
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Installing DNS (cont00)
DNS is not automatically added when member servers are promoted to domain controllers Use the Add/Remove Windows Components utility Verify that the DNS startup type is set to automaticIST363: Network Administration
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DNS Zones
DNS zones are part of the DNS namespace for which a DNS server is responsible- marshall.edu is used by Marshall to identify computers within Marshall University;
- To store the records for this domain, a zone on the DNS server needs to be created;
Once inside a zone, you can create DNS records A DNS server contains the zone for the marshall.edu domain; A top level DNS server contains the zone for the .edu domain and a DNS record that identifies the DNS server for marshall.edu domain; DNS server may also contain subdomains, e.g., ist.marshall.edu, math.marshall.edu, bio.marshall.edu; Subdomains are further divisions of the DNS namespace;IST363: Network Administration
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DNS Zones (cont00)
You designate whether a zone will hold records for forward lookups or reverse lookups A forward lookup zone holds records for forward lookups A reverse lookup zone holds records for reverse lookupsIST363: Network Administration
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Primary and Secondary Zones
It is helpful to keep copies of DNS domain information on more than one server: Fault tolerance; Reduce network traffic, e.g., keep a copy of DNS information at each physical location to reduce WAN traffic; It is essential that DNS servers automatically synchronize information between them Automates the process of AD replication;IST363: Network Administration
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Primary and Secondary Zones
A primary zone is the first zone to be created- Contains all the records created;
A secondary zone has copies of primary zone information Read-only copies of DNS resource records; You must edit the primary zone in order to create or modify resource records Changes will be copied to secondary zoneIST363: Network Administration
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Active Directory-Integrated Zones
An Active Directory-integrated zone stores information in Active Directory The DNS server must be a domain controller in order to store information in Active Directory Storing DNS information in Active Directory offers advantages over traditional primary and secondary zones Automatic backup of zone information; Multimaster replication; Increased security;IST363: Network Administration
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Caching-Only DNS Servers
These servers do not have any zones configured on them They exist only to be a local DNS server for client computers They cache first-time lookups They use cached information for subsequent client requests To create a caching-only server, install the DNS Service and do not create any zonesIST363: Network Administration
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Active Directory and DNS
Active Directory requires DNS to function properly The most important function that DNS performs for Active Directory is locating services, such as domain controllers To simplify management of DNS records for Active Directory, implement Dynamic DNSIST363: Network Administration
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Dynamic DNS
Allows records to be updated on a DNS server automatically Windows 2000/XP clients perform their own Dynamic DNS updates During the boot process, the clients contact their DNS server to perform a dynamic updateIST363: Network Administration
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Testing Dynamic DNS
Verify that a computer is registering a host name using Dynamic DNS Use the DNS snap-in to delete the A record used to map your host name to your IP address; Use the ipconfig /registerdns commandIST363: Network Administration
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Dynamic DNS and DHCP
The Dynamic DNS information updated by Windows 2000/XP is negotiated with the DHCP server during the lease process By default, a DHCP server running on Windows Server 2003 updates DNS records only for Windows 2000/XP clients if requestedIST363: Network Administration
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Creating a Root Server
Create a new Forward Lookup Zone, select primary zone option, uncheck the 00tore the zone in Active Directory00option; In the 00one name field00 type 0000; The DNS snap-in can be used to configure the server for this activityIST363: Network Administration
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Logging
DNS servers are capable of event logging and debug logging Event logging records errors, warnings, and information to the event log Debug logging records much more detailed informationIST363: Network Administration
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Logging (continued)
Event logging options include: No events Errors only Errors and warnings No events Debug logging options include: Packet direction Transport protocol Packet contents Packet typeIST363: Network Administration
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Lab 7 Assignment
Create screenshots of each step after each activity; Using the screenshots, write a manual for implementing and managing DNS; You can work on this by yourself, but I would suggest that you work with a partner to form a group of two.
