Q : What is DNS
Server?
Domain Name System is used to resolve domain name to
IP Address and also used to resolve IP Address to Domain Name. It has two zones
forward and Reverse Lookup Zone. Forward Lookup Zone resolve Domain name to IP
address. Reverse Lookup Zone is used to resolve IP address to Domain Name. Some
records associate with DNS
• A
Record binds Name with IP Address
• PTR
Record binds IP Address to Name
Q : What is the
Purpose of A and PTR Record?
• A
Record OR Host Record is used to bind a Name with IP Address.
• PTR
Record is used to bind an IP Address with Name.
Q : Explain SOA
Record.
Start Of Authority (SOA) Records indicate that Name
Server is authoritative server for the domain.
Q : Explain
different zone involved in DNS Server?
DNS has two different Zones Forward Lookup Zone and
Reverse Lookup Zone. There two Zones are categorized into three zones and are
as follows
Primary zone: It contains the read and writable copy
of the DNS Database.
Secondary Zone: It acts as a backup for the primary
zone and contains the read only copy of the DNS database.
Stub zone: It is also read-only like a secondary zone;
stub zone contains only SOA, copies of NS and A records for all name servers
authoritative for the zone.
Q. Explain
Briefly about Stub Zone?
It is also read-only like a secondary zone, so
administrators can't manually add, remove, or modify resource records on it.
But secondary zones contain copies of all the resource records in the
corresponding zone on the master name server; stub zones contain only three
kinds of resource records:
• A
copy of the SOA record for the zone.
• Copies
of NS records for all name servers authoritative for the zone.
• Copies
of A records for all name servers authoritative for the zone.
Q . Explain
some types of DNS records?
A Record: Binds an Name with an IP Address
PTR Record: Binds an IP Address with an Host Name
NS Record: Is name of an DNS Server
MX Record: Responsible for Mail receiving mail from
different MTA
Q. which are
the important configuration files for DNS server?
BIND uses /etc/named.conf as its main configuration
file, the /etc/rndc.conf file as the
configuration file for name server control utility
rndc, and the /var/named/ directory for zone files and the like.
Q. What is
BIND?
BIND stands for Berkeley Internet Name Domain which is
the most commonly used Domain Name System (DNS) server on the Internet.
Q. On which
version of bind u have worked?
BIND 9
Q. What is the
role of DNS?
A DNS server, or name server, is used to resolve an IP
address to a hostname or vice versa.
Q. On which
port DNS server works?
DNS servers use port 53 by default. Incoming and
outgoing packets should be allowed on
port 53. Also allow connections on port 921 if you
configure a lightweight resolver server.
The DNS control utility, rndc, connects to the DNS
server with TCP port 953 by default. If
you are running rndc on the name server, connections
on this TCP port from localhost
should be allowed. If you are running rndc on
additional systems, allow connections to
port 953 (or whatever port you have chosen to
configure) from these additional systems.
Q. What is
round robin DNS?
Round robin DNS is usually used for balancing the load
of geographically distributed Web servers. For example, a company has one
domain name and three identical home pages residing on three servers with three
different IP addresses. When one user accesses the home page it will be sent to
the first IP address. The second user who accesses the home page will be sent
to the next IP address, and the third user will be sent to the third IP
address. In each case, once the IP address is given out, it goes to the end of
the list. The fourth user, therefore, will be sent to the first IP address, and
so forth.
Q. What is Name
Server?
A name server keeps information for the translation of
domain names to IP addresses and IP
addresses to domain names. The name server is a program that performs the
translation at the request of a resolver or another name server.
Q. What is Primary name server or primary master
server?
Primary name server/primary master is the main data
source for the zone. It is the authoritative server for the zone. This server
acquires data about its zone from databases saved on a local disk. The primary
server must be published as an authoritative name server for the domain in the
SOA resource record, while the primary master server does not need to be
published.
Q. What is
Secondary name server/slave name server?
Secondary name server/slave name server acquires data
about the zone by copying the data from the primary name server (respectively
from the master server) at regular time intervals. It makes no sense to edit
these databases on the secondary name servers, although they are saved on the
local server disk because they will be rewritten during further copying.
Q. what is Root name server?
Root name server is an authoritative name server for
the root domain (for the dot). Each root name server is a primary server, which
differentiates it from other name servers.
Q. what is
Stealth name server?
Stealth name server is a secret server. This type of
name server is not published anywhere. It is only known to the servers that
have its IP address statically listed in their configuration. It is an
authoritative server. It acquires the data for the zone with the help of a zone
transfer. It can be the main server for the zone. Stealth servers can be used
as a local backup if the local servers are unavailable.
Q. What do you
mean by "Resource Records"?
nformation on domain names and their IP addresses, as
well as all the other information distributed via DNS is stored in the memory
of name servers as Resource Records (RR).
Q. Explain
"TTL"?
Time to live. A 32-bit number indicating the time the
particular RR can be kept valid in a server cache. When this time expires, the
record has to be considered invalid. The value 0 keeps nonauthoritative servers
from saving the RR to their cache memory.
Q. Tell me 5 Types
of DNS records?
A, NS, CNAME, SOA, PTR, MX.
Q. explain
"SOA Record"?
The Start of Authority (SOA) record determines the
name server that is an authoritative source of information for the particular
domain. There is always only one SOA record in the file, and it is placed at
the beginning of the file of authoritative resource records.
Q. what is
"A Record"
A (Address) records assign IP addresses to domain
names of computers. The IP address cannot have a dot at the end.
Q. Explain
"CNAME Record"?
Synonyms to domain names can be created using CNAME
records. This is often referred to as 'creating aliases for computer names'.
Q. What are
"HINFO and TXT Records"?
HINFO and TXT records are for information only. An
HINFO record has two items in its data part. The first item is information
about hardware, and the second one is information about software. A TXT record
contains a general data string in its data part.
Example :
test.com IN SOA ...
...
mail IN A 192.1.1.2
IN HINFO My_Server UNIX
IN TXT my server
...
Q. what are
"MX Records"?
MX records specify the mailing server of the domain.
An MX record shows to which computer a mail of a particular domain should be
sent. The MX record also includes a priority number, which can be used to
determine several computers where the mail for the domain can be sent. The
first attempt is to deliver the mail to the computer with the highest priority
(lowest value). If this attempt fails, the mail goes to the next computer (with
a higher priority value), and so on.
test.com IN SOA ...
...
mail
IN A 192.1.1.2
IN HINFO AlphaServer UNIX
IN TXT my
server
IN MX 30
mail2.nextstep4it.com
IN MX 20
mail3.nextstep4it.com
IN MX 10
mail2.nextstep4it.com
20} Explain "PTR Records"?
A Pointer Record (PTR) is used to translate an IP
address into a domain name.
Q. What is Dynamic
DNS?
Dynamic DNS a method of keeping a domain name linked
to a changing IP address as not all computers use static IP addresses.
Typically, when a user connects to the Internet, the user's ISP assigns an
unused IP address from a pool of IP addresses, and this address is used only
for the duration of that specific connection. This method of dynamically
assigning addresses extends the usable pool of available IP addresses. A
dynamic DNS service provider uses a special program that runs on the user's computer,
contacting the DNS service each time the IP address provided by the ISP changes
and subsequently updating the DNS database to reflect the change in IP address.
Q. What is the
role of "named-checkconf Utility"?
The named-checkconf utility checks the syntax of the
named.conf configuration file.
Syntax: named-checkconf [-t directory] [filename]
Q. what is the
role of "named-checkzone Utility"?
The named-checkzone utility checks the syntax and
consistency of the zone file.
Syntax:
named-checkzone [-dgv] [-c
class] zone [filename]
