|
IT Interview Questions:What Are Resource Records?
Information Technology (IT) Interview Questions and Answers
(Continued from previous question...)
IT Interview Questions:What Are Resource Records?
An RR is information related to a DNS domain; for example, the host record
defining a host IP address. Each RR will contain a common set of information,
as follows:
•
Owner Indicates the DNS domain in which the resource record is
found.
•
TTL
The length of time used by other DNS servers to determine how
long to cache information for a record before discarding it. For most RRs,
this field is optional. The TTL value is measured in seconds, with a TTL
value of 0 indicating that the RR contains volatile data that's not to be
cached. As an example, SOA records have a default TTL of 1 hour. This
prevents these records from being cached by other DNS servers for a longer
period, which would delay the propagation of changes.
Class
For most RRs,
this field is optional. Where it's used, it contains standard mnemonic text
indicating the class of an RR. For example, a class setting of IN indicates
the record belongs to the Internet (IN) class. At one time there were
multiple classes (such as CH for Chaos Net), but today, only the IN class is
used.
Type
This required field holds a standard mnemonic text indicating
the type for an RR. For example, a mnemonic of A indicates that the RR stores
host address information.
Record-Specific Data
This is a variable-length
field containing information describing the resource. This information's
format varies according to the type and class of the RR.
(Continued on next question...)
Other Interview Questions
| 