Practice Exams for Windows

Practice Exams for Windows

Saturday, 29 September 2007

DNS Zone Types (MCP Series)

Primary Zones - xyz.com
Secondary - xyz.com Transfered from Primary
ADI Zone - Replicated using Active Directory

Please note: You an mix and match Zone types when if each there is only one Zone type for any given domain. For Example: You cannot have a Primary and Secondary Zone for blah.com on one server.

Stub Zones - A Stub Zone only contains the the NS Records for each DNS Server, a SOA Record for the Primary DNS Server, A Records for each of the DNS Servers. The A Records bind the IP Address to the SOA or NS Records. Stub Zones are dynamic - When the DNS Records are updated or removed from the Zone this information is sent to the STUB Zone Server much like a Zone Transfer.

Conditional Forwarding - (Step 4 in DNS Resolution Order). Allows an Administrator to specify a DNS Server for a particular domain. Example tell all queries for blah.com to go to 1.1.1.1 and all other queries go to another DNS server (EG your ISP's DNS Server).

Conditional Forwarding is Static, Stub Zones are Dynamic.

Comparison of Secondary DNS, Stub Zones and Conditional Forwarding

Secondary DNS Server
Name Records Stored: All
When to use: When you need a copy of all DNS Records for the required Domain
Stub Zone
Name Records Stored: Basic DNS Data
When to use: When you only need a copy of basic DNS Records or to load balance
Conditional Forwarding
Name Records Stored: None
When to use: When you are not allowed to have any DNS data for the required domain

Notes: DNS Resolution Order
1. Local Cache
2. HOSTS File
3. Is this Server Autoritative?
4. Forwarding
5. Root Hints

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