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What is
Managed DNS?
The Domain Name System [DNS]
is a distributed database, arranged hierarchically,
containing records for domain names. The DNS system's
main aim is to match a domain name to an IP Address.
In order to fulfill this role, the DNS Server contains
Records [called Resource Records] in a Zone File,
which contains the domain name and IP address mappings for
computers contained within that Zone. All Resource Records
have a TTL [Time To Live], specifying the number
of seconds other DNS servers and applications are allowed
to cache the record.
Most Web Hosting
companies do not provide you with an interface to manage
your own DNS Records and/or the ability to select multiple
providers for various Services like Web Hosting, Mail
Hosting, etc.
guwahatiwebhosting gives
you complete control over the following Resource Records
by using our Managed DNS Service:
Address (A)
Records
>>
Mail
Exchanger (MX) Records
>>
Canonical Name (CNAME) Records
>>
Name Server
(NS) Records
>>
Start of
Authority (SOA) Parameters
>>
Address Record [A
Record]
The A Record is the most
basic and the most important DNS record type. They are
used to translate human friendly domain names such as "www.domain.com"
into IP-addresses such as 1.2.3.4 (machine friendly
numbers).
When you wish to host
your domain name, you will be provided with an IP address
that needs to be set as an A Record for that particular
domain name.
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Mail Exchanger [MX] Record
An MX Record identifies
the mail server(s) responsible for a domain name. When
sending an e-mail to user@xyz.com, your mail server
must first look up the MX Record for xyz.com to see
which mail server actually handles mail for xyz.com
(this could be mail.xyz.com - or someone else's
mail server like mail.isp.com). Then it looks up
the A Record for the mail server to connect to its
IP-address.
An MX Record has a
Preference number indicating the order in which the
mail server should be used (only relevant when multiple MX
Records are defined for the same domain name). Mail
servers will attempt to deliver mail to the server with
the lowest preference number first, and if
unsuccessful continue with the next lowest and so on.
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Canonical Name [Alias / CNAME] Record
CNAME Records are domain
name aliases. Often computers on the Internet have
multiple functions such as Web Server, FTP Server, Chat
Server, etc. To mask this, CNAME Records can be used, to
give a single computer multiple names (aliases).
Sometimes a single server
computer hosts many different domain names (take ISPs),
and so CNAME Records may be defined such as www.abc.com
= www.xyz.com.
The most popular
use of the CNAME Record type, is to provide access to a
Web Server using both the standard www.domain.com
and domain.com (without the www). This is usually
done by creating an A Record for the short name (without
www), and a CNAME-record for the www name pointing to the
short name.
CNAME Records can also be
used when a computer or service needs to be renamed, to
temporarily allow access through both the old and new
name.
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Authoritative Name Server [NS] Record
NS Records identify DNS
servers responsible (authoritative) for a Zone. A Zone
should contain one NS Record for each of its own DNS
servers (primary and secondaries). This mostly is used for
Zone Transfer purposes (notify). These NS Records have the
same name as the Zone in which they are located.
But the most important
function of the NS Record is Delegation. Delegation
means that part of a domain is delegated to other DNS
servers.
You can also delegate
sub-domains of your own domain name (such as
subdomain.yourname.com) to other DNS servers. An NS
Record identifies the name of a DNS server, not
the IP Address. Because of this, it is important
that an A Record for the referenced DNS server exists,
otherwise there may not be any way to find that DNS server
and communicate with it.
If an NS Record
delegates a sub-domain (subdomain.yourname.com)
to a DNS Server with a name in that sub-domain (ns1.subdomain.yourname.com),
an A Record for that server (ns1.subdomain.yourname.com)
must exist in the Parent Zone (yourname.com).
This A Record is referred to as a Glue Record,
because it doesn't really belong in the Parent Zone, but
is necessary to locate the DNS Server for the delegated
sub-domain.
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Start of Authority [SOA] Parameters
Each Zone contains one
SOA Record, which holds the following parameters for the
Zone
Name of Primary DNS
Server: The domain name of the Primary DNS Server for
the Zone. The Zone should contain a matching NS Record.
Mailbox of the
Responsible Person: The email address of the person
responsible for maintenance of the Zone.
Serial Number:
Used by Secondary DNS Servers to check if the Zone has
changed. If the Serial Number is higher than what the
Secondary Server has, a Zone Transfer will be initiated.
This number is automatically increased by our Servers when
changes to the Zone or its Records are made.
Refresh Interval:
How often Secondary DNS Servers should check if changes
are made to the zone.
Retry Interval:
How often Secondary DNS Server should retry checking, if
changes are made - if the first refresh fails.
Expire Interval:
How long the Zone will be valid after a refresh. Secondary
Servers will discard the Zone if no refresh could be made
within this interval.
Minimum (default) TTL:
Used as the default TTL for new records created within the
zone. Also used by other DNS Server to cache negative
responses (such as record does not exist, etc.). |