Monday, September 28, 2015

DNS Q & A PAGE - 1

DNS INTERVIEW QUESTIONS AND ANSWERS
PAGE - 1

1..What is DNS?

Domain N ame System (DN S) is the system that associates hostnames with IP addresses
2..What is the use of DNS?
This technique of abstracting IP addresses with symbolic names is called Domain Name Service (DNS)
IP-based networks, addressing and routing are performed using IP addresses
but people have difficulty remembering numbers so that’s why the
Domain Name System or DNS is necessary

DNS is also used for resolving information other than IP addresses

3..What is the DNS bit range?

IPv4  range is 32-bit address space and  IPv6 range is 128 bit  it can support larger subnet range
4..What is DNS lookup?
There are different DNS lookup utilities available from the command line. These will request a DNS server for an IP address resolution. host and nslookup are two DNS lookup utilities.

When host is executed it will list out all of the IP addressed attached to the domain name. nslookup is another command that is similar to host, which can be used to query details related to DNS and resolving of names
5..What you mean by Unknown Host?
This can be caused by the node not being listed in the /etc/hosts
file, failure of the DNS lookup, or a typo in a hostname definition. You can check DNS using the nslookup command. Check all three conditions when you get the Unknown host message.

 6..What does BIND Stands for ?
 BIND stands for Berkeley Internet Name Domain
7..What are all the  components of  BIND?
BIND comes with three components. The first is the service or daemon that runs the answering side of DNS.
The second item in the BIND bundle is the resolver library.
The third part of BIND provides tools such as the dig command for testing DNS.

8..What is dig?

dig is the last diagnostic utility, the  queries from
DNS servers and returns the information held about a particular domain.

9..What are zone files in DNS server ?

Files which contain the data being served by the DNS system are called  Zone Files

10..What are the different types of Resource Records in bind ?

NS, CNAME , MX, PTR, SOA

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