WINS Replicatio

When two WINS servers are configured to communicate with each other replication occurs any time the data base on one of them changes. Servers are configured as a push or pull partner. A server can be both a push and pull partner. Push partners send update notices when a database change is made. A pull partner asks push partners for database entries more recent than their current listings. Only changes are replicated. Pull servers are used across slow links since pull requests can be set for specific times.

• A pull server will pull updates when it is started, then at chosen times thereafter.
• A push partner will send updates when a change threshold is reached. A thershold and update interval may be set.

Windows 2000 DNS In Windows 2000, DNS is required to use Active Directory. Domain Name Service is used to change internet domain and computer computer names into IP addresses and vice versa. DNS works at the application layer and uses TCP and UDP for transport. TCP is only used if returned data is truncated. See the DNS section in the Networking Guide for information about DNS. DNS was originally based on HOSTS files that were maintained by a centralized Network Information Center. Today of is based on a hierarchy of servers with a distributed hierarchial database throughout the network or internet. DNS Levels DNS is a hierarchial naming structure with the following levels: Root designated by a dot (.). First level - This indicates country or type of organization such as "org", "com", and "net". Second level - Indicates the organization name and can be purchased for a yearly fee. Notice that the highest level of the domain is listed last. An example of a domain name that you may be familiar with is: comptechdoc.org. DNS Operation

DNS Servers

On the client side, a DNS resolver is used to send queries to DNS servers. The resolver is normally part of a library routine or it is built into the application. DNS uses zone files to keep name and IP address database information for the internet domain or hierarchial set of domains. Zones are a storage of information in a file for a DNS domain or DNS subdomains (DNS domains are not the same as Windows domains). DNS does not yet support dynamic configuration but has been modified for Windows systems to do so. Different aliases may be created by the administrator for the same host. Three types of name servers as defined by how it relates to the zone information:

• Primary - Locally stored files exist on the name server data base. The master zone file copy is stored here.
• Secondary - Gets data called a zone transfer from another server that is the zone authority.
• Caching Only - Caches name server information and does not contain its own files.

A primary and secondary name server should be used on a network. When a zone is defined, some server must be configured to be a master name server for the zone. There can be different master name servers for different zones. The master server provides copies of the zone information to the secondary DNS server. Name servers can be configured to get information from other name servers when the information is not found in the local database. These types are forwarders and slaves. Name servers as categorized by function:

• Master - The zone authority that contains the master zone files.
• Forwarders - A name server that passes name resolution requests to other name servers. This configuration is done on a per server basis.
• Slaves - Slave name servers are configured to use forwarders.

Windows introduces additional terminalogy:

• Standard primary - The same as a primary DNS server listed above. This is a master server by function.
• Active Directory Integrated (primary) - DNS entries are stored with Active Directory data rather than a normal zone file. More than one of these Active Directory primary servers may exist due to Active directory replication. This term is used to refer to both the Active Directory Integrated zones and files that support the zone.
• Standard secondary - The same as a secondary DNS server listed above. This is a slave server by function.
• Root server - The server that has the DNS data for the root zone. The root zone is the organization internal network root zone or internet root zone. It is used when a private network is not directly on the internet (no connection or via proxy server).

If the DNS server is connected to the internet, the DNS Server Wizard will not allow the DNS server to be configured as a root server.

Queries

Query types are:

• Inverse - Getting the name from the IP address. These are used by servers as a security check.
• Iterative - Server gives its best answer. This type of inquiry is sent from one server to another.
• Recursive - Cannot refer the query to another name server.

Zone Transfers

The DNS zone file serial number is used to trach DNS changes. The notify function is used to initiate zone transfers. Zone transfer types are:

• Full - AXFR Query - Secondary server refresh interval expires and it sends an AXFR qurey.
• Incremental - IXFR query - Only new or updated entries are copied.

DNS Zones

Possible zones include:

• Forward lookup zone - Name to IP address map.
• Reverse lookup zone - IP address to name map.
• Standard primary zone (primary zone) - A master copy of a forward or reverse lookup zone.
• Active Directory integrated zone - A copy of a standard primary or Active Directory integrated zone. The IP address and computer name is stored in Active Directory and replicated to all local domain controllers. DNS information is not replicated to domain controllers outside the domain.
• Standard secondary zone (secondary zone)