Robust Networking Infrastructure
Windows 2000 Professional makes configuring and using networking technology easier with features such as Network and Dial-up Connections. It also includes numerous networking features to take advantage of the latest TCP/IP networking innovations and standards, such as Layer Two Tunneling Protocol (L2TP), Internet Protocol security (IPSec), Internet Connection Sharing, Quality of Service (QoS), and dynamic multi-link dialing. For more information about Network and Dial-up Connections, see "Local and Remote Network Connections" in this book.
When using Windows 2000 Professional with Windows 2000 Server, you can take advantage of many server-based networking features and services, such as the Windows 2000 implementations of DNS, and the WINS name-resolution services that provide interoperability with previous versions of Windows. For more information about the networking features included with Windows 2000 Server, see the TCP/IP Core Networking Guide. For more information about the networking features in Windows 2000 Professional, see Part 4, "Network Configuration and Management" and Part 5 "Network Interoperability" in this book
Domain Name System (DNS) is the default naming system for Internet Protocol (IP)-based networks. It enables users to use hierarchical, display names to easily locate computers and other resources on an IP network. Using Windows 2000 Professional with Windows 2000 Server allows you to take advantage of the new features and enhancements in the Windows 2000 implementation.
Windows 2000 DNS is compliant with standard DNS as described in the Request for Comments (RFC) documents of the Internet Engineering Task Force (IETF). Because Windows 2000 DNS is RFC-compliant, it provides interoperability with most of the other DNS server implementations, such as those DNS servers that use the Berkeley Internet Name Domain (BIND) software.
The Windows 2000 implementation of DNS has several new features and improvements over Windows NT 4.0, including the following:
Support for Active Directory as a Locator Service for Domain Controllers DNS is required to locate Active Directory objects. You can also use a third-party DNS server implementation solution to support Active Directory deployment.
Integration with Active Directory You can integrate DNS zones into Active Directory to provide increased fault tolerance and security. Every Active Directory-integrated zone is replicated among all domain controllers within the Active Directory domain. All DNS servers running on these domain controllers can act as primary servers for the zone, accepting dynamic updates. Active Directory replicates on a per-property basis, propagating only relevant changes.
Support for Dynamic Updates The DNS service allows client computers to dynamically update their resource records in DNS. This improves DNS administration by reducing the time needed to manually manage zone records. The dynamic update feature can be used in conjunction with Dynamic Host Configuration Protocol (DHCP) to update resource records when a computer's IP address is changed. Computers running Windows 2000 can send dynamic updates.
Support for Aging and Scavenging Records The DNS service can scan and remove records that are no longer needed records. When enabled, this feature can prevent stale records from remaining in the DNS.
Support for Secure Dynamic Updates in Active Directory-Integrated Zones You can configure Active Directory-integrated zones for secure dynamic update so that only authorized users can make changes to a zone or record.
Easier Administration The DNS console for managing the DNS service offers an improved graphical user interface (GUI) over Windows NT 4.0. Windows 2000 Server provides several new configuration wizards and tools to help you manage and support DNS servers and clients on your network.
Administration from the Command Prompt You can use the command-line tool Dnscmd.exe for most tasks that you can perform from the DNS console, such as:
Creating, deleting, and viewing zones and records
Resetting server and zone properties
Performing routine administrative operations, such as:
Updating the zone
Reloading the zone
Refreshing the zone
Writing the zone back to a file or Active Directory
Pausing and resuming the zone
Clearing the cache
Stopping and starting the DNS service
Viewing statistics
You can also use Dnscmd.exe to write scripts for remote administration. For more information about Dnscmd.exe, see Windows 2000 Support Tools Help. For information about installing and using the Windows 2000 Support Tools and Support Tools Help, see the file Sreadme.doc in the directory SupportTools on the Windows 2000 operating system CD.
Enhanced Name Resolution The Windows 2000 DNS resolver tries to resolve names with DNS before trying to use Network Basic Input/Output System (NetBIOS). Also, it can query different servers based on the adapters to which they are assigned.
Enhanced Caching and Negative Caching You can view and flush the resolver cache by using the command-line tool Ipconfig, and you can flush the server cache from within the DNS console. Also, the resolver performs negative caching, which remembers that a name or type of record does not exist. Negative caching reduces lookup time when the user queries for a name that the resolver has already determined does not exist.
Additional Client Enhancements The cache can be preloaded with Hosts file entries (a file that contains a mapping of computer names to IP addresses). Also, the resolver server list can be dynamically reordered to prioritize responsive DNS servers.
Support for DNS in Mixed Environments If all of the computers on your network are running Windows 2000, you do not need any WINS servers. Even in a mixed environment, you do not need to configure WINS on your Windows 2000-based clients if you have configured WINS lookup. By using WINS lookup, you can direct a Windows 2000 DNS server to query WINS for name resolution, so that DNS clients can look up the names and IP addresses of WINS clients.
Interoperability with Other DNS Server Implementations Because the Windows 2000 DNS server is RFC-compliant, it works with other DNS server implementations, such as BIND.
Integration with Other Network Services The Windows 2000 DNS server is integrated with DHCP and WINS.
Incremental Zone Transfer In addition to performing full zone transfers (sending a copy of the entire zone), the DNS server can send and receive incremental zone transfers, in which only changes to the zone are transferred. This can reduce the amount of time and bandwidth required for zone transfers.
For information about DNS and the Windows 2000 implementation of DNS, see "Introduction to DNS" and "Windows 2000 DNS" in the TCP/IP Core Networking Guide.
Dynamic Host Configuration Protocol (DHCP) is a TCP/IP standard that reduces the complexity and administrative overhead of managing network client IP address configuration. Windows 2000 Server provides the DHCP service, which enables a computer to function as a DHCP server and to configure DHCP-enabled client computers on your network. DHCP runs on a server, enabling the automatic, centralized management of IP addresses and other TCP/IP configuration settings for client computers on your network. The DHCP service also provides integration with Active Directory and the DNS service, enhanced monitoring and statistical reporting for DHCP servers, vendor-specific options and user-class support, multicast address allocation, and rogue DHCP server detection.
DHCP simplifies the administrative management of IP address configuration by automating address configuration for network clients. A DHCP server is any computer running the DHCP service. The DHCP server automatically allocates IP addresses and related TCP/IP configuration settings to DHCP-enabled clients on the network.
Every interface on a TCP/IP-based network must have a unique IP address to access the network and its resources. Without DHCP, IP configuration must be done manually for new computers, for computers moving from one subnet to another, and for computers that have been removed from the network.
By deploying DHCP in a network, this process is automated and centrally managed. The DHCP server maintains a pool of IP addresses and leases an address to any DHCP-enabled client when it logs on to the network. Because the IP addresses are dynamic (leased) rather than static (permanently assigned), addresses no longer in use are automatically returned to the pool for reallocation.
The DHCP service for Windows 2000 Server is based on IETF standards, and DHCP specifications are defined in RFCs. The following RFCs specify the core DHCP standards that Microsoft supports with its DHCP service:
RFC 2131: Dynamic Host Configuration Protocol (replaces RFC 1541)
RFC 2132: DHCP Options and BOOTP Vendor Extensions
For more information about the Windows 2000 DHCP support, see "Dynamic Host Configuration Protocol" in the TCP/IP Core Networking Guide.
Quality of Service (QoS) facilitates the deployment of media-rich applications, such as video conferencing and IP telephony, without adversely affecting network throughput. Windows 2000 QoS also improves the performance of mission-critical software such as Enterprise Resource Planning (ERP) applications. Windows 2000 supports the QoS Admission Control Service, a policy mechanism that offers the ability to centrally designate how, when, and by whom network resources are used on a per-subnet basis. QoS is an emerging technology, with standards that are being developed and revised based on customer feedback and industry-wide cooperation.
QoS is a set of methods and processes that a service-based organization implements to maintain a specific level of quality. In the context of networking, QoS refers to a combination of mechanisms that provide a specific quality level to application traffic on a network or on multiple networks. Implementing QoS means combining a set of IETF-defined technologies to alleviate the problems caused by shared network resources and finite bandwidth.
QoS provides two distinct benefits:
A mechanism for applications to request service quality parameters, such as low network delay.
Higher levels of administrative control over congested subnet bandwidth resources.
Implementing QoS enables administrators to make the most efficient use of subnet bandwidth when deploying resource-intensive applications. A QoS-enabled network provides guarantees for sufficient resources; this gives a congested, shared network segment a level of service approaching that of a private network. Different classes of applications have varying degrees of tolerance for delay in network throughput. A QoS guarantee ensures that an application can transmit data in an acceptable way, in an acceptable time frame so that the transmission is not delayed, distorted, or lost.
To uphold such guarantees, QoS requires cooperation from the sending and receiving hosts (end nodes), the data link layer (open systems interconnection reference model [OSI] model layer 2) devices (switches), the network layer (OSI model layer 3) devices (routers), and any wide area network (WAN) links in between. Without QoS, each of these network devices treats all data equally and provides service on a first-come, first-served basis. In addition, an application must have some level of QoS awareness so that it can request bandwidth and other resources from the network.
The efficient use and allocation of bandwidth is critical for productivity. Real-time applications, media-rich applications, and Enterprise Resource Planning applications require a large amount of uninterrupted bandwidth and can strain existing network resources. When traffic is heavy, overall performance degrades and results in traffic delay and packet loss. This degradation causes problems with video conferencing, real-time audio, and interactive communication, causing distortion of voices and images. Because media-rich applications use large quantities of bandwidth, traditional mission-critical applications suffer from the lack of available resources. QoS provides a delivery system for network traffic that guarantees limited delays and data loss.
It is important to realize that QoS cannot create bandwidth; it can only efficiently partition bandwidth based on different parameters.
For information about the Windows 2000 implementation of QoS, see "Quality of Service" in the TCP/IP Core Networking Guide.
While Windows 2000 uses Domain Name System (DNS) as its primary method for matching a host name to its IP address, Windows 2000 also supports Windows Internet Name Service (WINS) for matching a NetBIOS name to its IP address. WINS is the name resolution system used for Windows NT Server 4.0 and earlier operating systems.
Windows 2000 DNS uses hierarchical fully qualified domain names (FQDNs) rather than the flat NetBIOS naming conventions supported by WINS. However, WINS provides an important service for network administrators with heterogeneous systems that support clients running older operating systems, such as Windows 95 and Windows NT 4.0. These systems do support DNS name resolution but do not support dynamic updates to DNS records.
For more information about WINS, see "Windows Internet Name Service" in the TCP/IP Core Networking Guide.