Any answer from a DNS nameserver query takes the form of a resource record (generally referred to as an RR). Resource records look like this: NAME TTL CLASS TYPE RDATA
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Resource Records |
Any answer from a DNS nameserver query takes the form of a resource record (generally referred to as an RR). Resource records look like this: NAME TTL CLASS TYPE RDATA
NAME: The host is that which is being queried. If we were querying dns1.easystreet.com for "www.easystreet.com", "www.easystreet.com" would be the NAME.
TTL: Time To Live is a 32-bit integer stating how long in seconds a nameserver or the user making the query should cache the results returned for this record. Values of zero in this section declare the record uncachable.
CLASS: This is assumed to be 1 or IN in all cases. Other classes (CSNet (2), BIND's Chaos (3), MIT's Hesiod (4)) are essentially deprecated and unlikely to be found.
TYPE: Any one of many possible RR types (RRTs). A fairly full listing of relevant TYPES can be found on IANA.
RDATA: Dependent upon RRT and described below.
| TYPE | RDATA |
Example
|
Description |
| A | Dotted quad |
206.102.12.130
|
Contains the IPv4 address that the domain resolves to. If there are multiple, generally a random one is chosen by the system making the query to use. |
| AAAA | hexadecimals seperated by colons |
2001:6B0:1:EA:A00:20FF:FE8F:708F
|
Contains the IPv6 (post-experimental replacement for IPv4) equivalent of A. |
| NS | Domain name |
dns2.easystreet.com.
|
Contains the domain name a nameserver of the domain. Any domain must have at least two nameservers. |
| SOA | Domain name of primary, domain name of hostmaster, serial, refresh, retry, expiration, default time to live |
dns1.easystreet.com. hostmaster.easystreet.com. (
|
Start of a zone of authority. This declares a nameserver which is "authoritative" for the domain; any queries (about any domains under the authority) sent to this nameserver will be firsthand and accurate, not cached. |
| MX | Preference number, domain name |
100 smtp.easystreet.com.
|
The domain specified is designed to deal with all email sent to NAME. Also given is a mailing priority in case one machine rejects or fails to respond to sent emails. "1" is first priority. |
| CNAME | Domain name |
easystreet.com.
|
A canonical domain name for the queried domain. The specified domain is considered equivalent to the queried domain for mailers and other programs. |
| PTR | Domain name |
easystreet.com.
|
A pointer to another domain. Similar to CNAME, except that the queried domain is not equivalent to the referenced domain. |
| TXT | Arbitrary text |
"You" "should" "follow" "standards" "and" "use" "www."
|
Descriptive text for the queried domain. |
| NULL | Unstandardized data | Space used when testing experimental DNS functions. The "NULL" record can safely be ignored by users and isn't allowed on master servers. | |
| MD | Domain name |
mail.easystreet.com.
|
Mail destination capable of acting as a mail agent and accepting mail for the domain. |
| MF | Domain name |
mail.easystreet.com.
|
Mail forwarder capable of accepting mail and sending it to another system. |
| HINFO | CPU type string, OS type string |
"sun-ultra1" "unix"
|
Host information used by some special software. |
| MINFO | RMAILBX, EMAILBX |
mail.easystreet.com. mail.easystreet.com.
|
Mailing information generally used for mailing lists. RMAILBX is the responsible mail box used for the mailing list, EMAILBX is the error mail box to which problems are sent. |
NAME
TTL
CLASS
TYPE
RDATA
easystreet.com.
3600
IN
NS
dns1.easystreet.com.
easystreet.com.
3600
IN
NS
dns2.easystreet.com.
easystreet.com.
3600
IN
NS
dns3.easystreet.com.
easystreet.com.
3600
IN
SOA
hostmaster.easystreet.com. (
2003042840 ;serial (version)
14400 ;refresh period (4 hours)
900 ;retry interval (15 minutes)
604800 ;expire time (1 week)
3600 ;default ttl (1 hour)
)
easystreet.com.
3600
IN
A
206.102.12.130
easystreet.com.
3600
IN
MX
100 smtp.easystreet.com.
easystreet.com.
3600
IN
MX
120 mxqueue.easystreet.com.
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