NA Lesson - 23

Deploying DNS Servers (Part-2)

DNS Server Types

• The DNS server type refers to the type of zone the server is hosting—or, in the case ofcaching-only servers, whether it is hosting a zone at all. 
• The various types of DNS servers are given below :

 i.    Primary Servers     
 ii.   Secondary Servers    
 iii.  Stub Servers 
  iv. Caching-Only Servers

 i.Primary Servers 

•  A primary server is created when a primary zone is added, either through the New Zone Wizard, the Configure A DNS Server Wizard, or command-line tools.

• The primary server for a zone acts as the zone’s central point of update. Newly created zones are always this type. We can deploy primary zones in one of two ways: as standard primary zones or with Active Directory integrated primary zones.

     ii.Secondary Servers

• A standard primary zones, requires a secondary server is required to allow the zone to appear to other DNS servers in the network. Secondary servers provide a means to offload DNS query traffic in areas of the network where a zone is heavily queried and used.

• Additionally, if a primary server is down, a secondary server provides name resolution in the zone until the primary server is available.

     iii.Stub Servers 

•  Stub DNS servers host stub zones: abbreviated copies of a zone that contain only a list of the authoritative name servers for its master zone.

• A DNS server hosting a stub zone attempts to resolve queries for computer names in the master zone by querying these name servers listed. Stub zones are most frequently used to enable a parent zone to keep an updated list of the name servers available in a child zone.

      v.            iv.Caching-Only Servers

• Caching-only servers do not host any zones and are not authoritative for any particular domain. The information they contain is limited to what has been cached while resolving queries.

• In determining when to use this kind of server, note that when it is initially started, it has no cached information. The information is obtained over time as client requests are serviced.

By default, the DNS Server service acts as a caching-only server. Caching-only servers thus require little or no configuration.

To install a caching-only DNS server, complete the following steps:

1. Install the DNS server role on the server computer.

2. Do not configure the DNS server (as you might normally) to load any zones.

3. Verify that server root hints are configured or updated correctly.

Q. Discuss the essential features of various DNS server Types.