The Domain Name Service (DNS) is the IETF’s standard for providing name resolution over the TCP/IP protocol. Alternatively, for NetBIOS networks running the TCP/IP protocol, the Windows Internet Naming Service (WINS) is the IETF’s standard for providing additional name resolution capabilities. This paper will review each network operating system’s ability to provide a standards-compliant, operating system-integrated DNS implementation. Additionally, each operating system will be evaluated on its ability to provide value-added services to enhance the deployment and management of the DNS implementation.
Solaris 7 Implementation Details
Solaris 7 provides full support for the Domain Name Service (DNS). The Solaris 7 DNS implementation is fully compatible with BIND 4.9.3 and all current IETF RFCs that cover DNS. But DNS is not the primary name service for Solaris 7. That role is the responsibility of the Network Information Service + (NIS+), which is discussed later under “Management and Directory Services.”
DNS configuration can be managed through the Solaris Administration wizards. These administration wizards are run through the Solaris Management Console or from the command line. The DNS Server Configuration wizard is used to configure DNS servers. The DNS Client Configuration wizard is used to configure DNS clients. Both wizards have a fairly efficient graphical user interface that allows you to configure DNS.
When running Solaris PC NetLink and emulating a Windows NT domain controller, Solaris 7 provides full support for WINS. This support is the same as that provided in Windows NT Server 4.0.
Windows NT Server 4.0 Implementation Details
Microsoft Windows NT Server 4.0 provides two name resolution facilities – standard DNS and the Windows Internet Naming Service (WINS). The DNS implementation is relatively standardized and provided interoperability between Windows NT 4.0-based machines running TCP/IP and the Internet. WINS provided additional name resolution capabilities for NetBIOS-based computer systems running on top of the TCP/IP protocol.
The DNS implementation represents a relatively standardized implementation of BIND 4.9, conforming to IETF RFCs 1034 and 1035. DNS information is stored in an ASCII-text based database in BIND 4.9 format. Administration is accomplished either using a GUI-based tool, the DNS Manager, or by editing the ASCII-text databases directly using a text editor.
As with BIND 4.9, the Windows NT Server 4.0 DNS implementation can serve as either a primary or secondary name server for any given zone. Interoperability with other DNS servers is also provided as with any BIND 4.9 implementation.
WINS is an implementation of the IETF standards for providing NetBIOS browsing and name resolution over the TCP/IP protocol, as defined in RFCs 1001 and 1002., In addition to providing machine name and TCP/IP address mapping, it helps provide browsing and service location for such things as domain controllers and workgroups. WINS allows for dynamic updates and provides for full interoperability with the DHCP protocol for instant machine name and TCP/IP address mappings.
The DNS and WINS server implementations are fully integrated to provide some dynamic DNS capabilities. Any Windows NT Server 4.0 DNS server that is the primary name server for a given zone can reference the WINS database, providing instant, dynamic DNS updates via WINS.
Windows 2000 Server Implementation Details
Microsoft Windows 2000 Server improves on the functionality of the name resolution services from Microsoft Windows NT Server 4.0.onIt offers a highly enhanced name resolution solution.
The DNS implementation in Windows 2000 Server has been totally reworked to take advantage of Active Directory services and to provide support for the latest IETF standards for the management of dynamic addresses and name resolution. At the standards level, the DNS implementation remains based on the IETF RFCs 1034 and 1035. However, additional support for the official IETF working draft of the Dynamic DNS update – RFC 2136 – has been provided.
Configuration and Management
Management of DNS services is now performed entirely through the new Microsoft Management Console (MMC), making administration considerably easier. MMC provides a consistent look with other Windows 2000 management packages. For the first time, remote management of DNS servers is supported via MMC. Wizards have been added to the MMC, making DNS configuration easier than it is on other platforms.
Windows 2000 Server also supports Dynamic DNS, providing instant DNS registration for DHCP-configured hosts. Unlike other implementations, Windows 2000 Server is based on the proposed IETF standard and therefore will interoperate with other dynamic DNS systems as they become available.
DNS Resolver Cache
A DNS Resolver Cache service also has been added to speed DNS queries. This service greatly reduces DNS network traffic, and speeds name resolution by providing a local cache for DNS queries on all Windows 2000-based servers.
Finally, the DNS service has been fully integrated with Active Directory, which natively uses the Windows 2000 Server DNS implementation as its naming resolution service. Domain names on Windows 2000 Server are now DNS domain names. Consequently, “Microsoft.com” is a valid DNS domain and is also a valid Active Directory domain; the two are one and the same. Tight directory integration means that the Active Directory fits naturally into intranet environments and the Internet. There is no additional overhead or effort required to manage DNS.
When Active Directory is installed on a server, it publishes itself via Dynamic DNS. All DNS information is stored using the Active Directory client/server database engine (based on the Microsoft ESE97 engine), providing a significantly higher level of performance and database reliability than is available with text-based databases. (Non-Active Directory DNS implementations still use the BIND 4.9 text-based database format.) DNS information can be automatically replicated to other DNS servers throughout the Active Directory organization, providing additional levels of fault-tolerance. Finally, the DNS database can be physically configured in a true hierarchy. This will allow each workgroup to seamlessly manage its portion of DNS. It eliminates the need to have the entire DNS database replicated in full throughout an organization, and it provides transparent access to the end users with no need to reference specific DNS servers.
The WINS services are enhanced in Windows 2000 Server to continue to provide NetBIOS-based TCP/IP name resolution services. New features include Persistent Connections, Manual Tombstoning, MMC-based management, enhanced filtering and record searching, dynamic record deletion and multi-select, and record verification and version number validation.
Persistent Connections allow each WINS server to maintain a dedicated connection with one or more replication partners, eliminating the overhead of opening and closing connections. The benefit to users is improved replication speed. Manual Tombstoning allows for a tombstone marker for deleted records to be propagated to all WINS servers. This prevents undeleted record copies from reappearing on other WINS servers and then being re-propagated back into the network. MMC is now used for all WINS management, providing a more user-friendly and powerful environment for administrators.
Administrators can now search for records of interest by showing only those that fit a specific criterion through the new MMC tool. The user interface has also been improved to allow dynamic records to be manually deleted (this was previously not possible). Multiple deletions can be made simultaneously. Finally, new tools verify consistency between WINS servers, allowing systems administrators to monitor the enterprise more accurately.
Windows 2000 Server supports both DNS and WINS. Both naming services are compliant with all of the latest IETF RFCs. Dynamic DNS and DHCP integration is fully supported and implemented according to the latest IETF specifications. The MMC-based management tools provide an easy-to-use graphical user interface for managing name resolution services and are also well-suited for novice administrators.
Solaris 7 offers a comprehensive DNS facility that is standards-based. While Solaris 7 supports current IETF RFCs related to DNS, it does not support dynamic DNS technology at this time. Additionally, SOLARIS 7 does not provide native support for WINS. WINS support is only available through Solaris PC NetLink.
Windows NT Server 4.0 name resolution services represents the most dated of the three operating systems. Both DNS and WINS are supported and both implementations are in compliance with IETF specifications. The DNS implementation is merely an implementation of BIND 4.9 with a GUI management tool – no additional features or capabilities such as Dynamic DNS are present. WINS and DNS can be integrated to provide pseudo-Dynamic DNS functionality, but this is a rather limited and non-standardized solution. Additionally, although adequate, the GUI management tools are an entire generation behind Windows 2000 Server in ease-of-use and functionality.