Tuesday, December 8, 2009

DNS Interview Questions And Answers

1.What is DNS?
Domain Naming Services or System: - used for resolving host names to IPs and IPs to Host Names.

2.What is NBNS?
NetBIOS Naming System, ex. - WINS, 2k access resources using DNS naming Conventions

3.What is a Forward Lookup?
Resolving Host Names to IP Addresses

4.What is Reverse Lookup?
It’s a file contains host names to IP mapping information.

5.What is a Resource Record?
It is a record provides the information about the resources available in the N/W infrastructure.

6.What are the diff. DNS Roles?
Standard Primary, Standard Secondary, & AD Integrated.

7.What is a Zone?
Zone is a sub tree of DNS database.

8.What is primary, Secondary, stub & AD Integrated Zone?
Primary Zone: - zone which is saved as normal text file with filename (.dns) in DBS folder. Maintains a read, write copy of zone database
Secondary Zone: - maintains a read only copy of zone database on another DNS server. Provides fault tolerance and load balancing by acting as backup server to primary server.
Stub zone: - contains a copy of name server and SOA records used for reducing the DNS search orders. Provides fault tolerance and load balancing.

9.What does a zone consist of & why do we require a zone?
Zone consists of resource records and we require zone for representing sites.

10.What is Caching Only Server?
When we install 2000 & 2003 server it is configured as caching only server where it maintains the frequently accessed sites information and again when we access the same site for next time it is obtain from cached information instead of going to the actual site.

11.What is forwarder?
When one DNS server can’t receive the query it can be forwarded to another DNS once configured as forwarder.

12.What is secondary DNS Server?
It is backup for primary DNS where it maintains a read only copy of DNS database.

13.How to enable Dynamic updates in DNS?
Start>Program>Admin tools> DNS >Zone properties.

14.What are the properties of DNS server?

15.Properties of a Zone?
General, SOA, NAMESERVER, WINS, Security, and ZONE Transfer.

16.What is scavenging?
Finding and deleting unwanted records.

17.What are SRV records?
SRV are the service records, there are 6 service records. They are useful for locating the services.

18.What are the types of SRV records?
MSDCS:Contains DCs information
TCP:Contains Global Catalog, Kerberos & LDAP information.
UDP:Contains Sites information
Sites:Contains Sites information
Domain DNS Zone:Conations domain’s DNS specific information
Forest DNS zone:Contains Forest’s Specific Information.

19.Where does a Host File Reside?

20.What is SOA?
Start of Authority: useful when a zone starts. Provides the zone startup information

21.What is a query?
A request made by the DNS client to provide the name server information.

22.What are the diff. types of Queries?
Recursion, iteration

23.Tools for troubleshooting DNS?


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