Dns interview

1) What is DNS?
The Domain Name System (DNS) is a hierarchical distributed naming system for
computers. The Domain Name System distributes the responsibility of assigning domain
names and mapping those names to IP addresses by designating authoritative name
servers for each domain. Authoritative name servers are assigned to be responsible for their
particular domains, and in turn can assign other authoritative name servers for their subdomains.
2) What is the main purpose of a DNS server?
DNS servers are used to resolve FQDN hostnames into IP addresses and vice versa.
3) How does a computer know to which DNS server it has to sent the request
The DNS server IP address is configured on the TCP/IP adapter setting of the computer.
With this information, the computer knows the DNS server to which the request has to be
sent.
4) What is the port no of DNS?
UDP port number - 53
5) How many root DNS servers are available in the world?
13
6) What is a Forward Lookup?
Resolving Host Names to IP Addresses, Address mapping (A) records maps a host name to
an IP address
7) What is a Forward Lookup?
Reverse-lookup pointer (PTR) records map an IP address to a host name.
8) What is a Resource Record?
It is a record provides the information about the resources available in the N/W
infrastructure.
9) What is the different DNS Roles?
Standard Primary, Standard Secondary, & AD Integrated.
10) What is a Zone?
Zone is a sub tree of DNS database.
11) Why we create PTR Records
Secure services in your network require reverse name resolution to make it more difficult to
launch successful attacks against the services. To set this up, you configure a reverse
lookup zone and proceed to add records.
12) SOA records must be included in every zone. What are they used for?
SOA records contain a TTL value, used by default in all resource records in the zone. SOA
records contain the e-mail address of the person who nis responsible for maintaining the
zone. SOA records contain the current serial number of the zone, which is used in zone
transfers.
13) What is primary, Secondary, stub & AD Integrated Zone?
Primary Zone: - zone which is saved as normal text file with filename (.dns) in DBS folder. Holds the
master copy of a zone and can replicate it to secondary zones. All changes to a zone are made on the
standard primary.
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.Information in a
primary zone is replicated to the secondary by use of the zone transfer mechanism.

Stub zone: - contains a copy of name server and SOA records used for reducing the DNS search
orders. Provides fault tolerance and load balancing.
Active Directory-integrated: -A Microsoft proprietary zone type, where the zone information is held
in the Windows 2000 Active Directory (AD) and replicated using AD replication.
DNS record types
14) What is the main purpose of SRV (Service)records?
SRV records are used in locating hosts that provide certain network services.
15) Which of the following conditions must be satisfied to configure dynamic DNS updates
for legacy clients?
The zone to be used for dynamic updates must be configured to allow dynamic updates. The DHCP
server must support, and be configured to allow, dynamic updates for legacy clients.
16) Benefits of using AD-integrated zones.
a) Active Directory integrated DNS enables Active Directory storage and replication of DNS zone
databases. Windows 2000 DNS server, the DNS server that is included with Windows 2000 Server,
accommodates storing zone data in Active Directory.
b) When you configure a computer as a DNS server, zones are usually stored as text files on name
servers that is, all of the zones required by DNS are stored in a text file on the server computer.
c) These text files must be synchronized among DNS name servers by using a system that requires a
separate replication topology and schedule called a zone transfer However, if you use Active Directory
integrated DNS when you configure a domain controller as a DNS name server, zone data is stored as
an Active Directory object and is replicated as part of domain replication.

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?
INTERFACES, FORWARDERS, ADVANCED, ROUTINGS, SECURITY, MONITORING, LOGGING, DEBUG
LOGGING.
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?
c:windowssystem32driversetc.
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?
DNS Console, NSLOOKUP, DNSCMD, IPCONFIG, Logs, PM.

Dns interview

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Dns interview