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The order of transmission is resolved to the octet level. Whenever an octet represents a numeric quantity, the left most bit is the high order or most significant bit.

An entire domain name or a list of labels is replaced with a pointer to a prior occurrence of the same name. The pointer takes the form of a two-octet sequence: 11|OFFSET.

A name server must employ multiple concurrent activities. It is simply not acceptable for a name server to block the service of UDP requests while it waits for TCP data.

It is very important that when a zone is refreshed, queries should not use old and new data simultaneously.

The MINIMUM value in the SOA should be used to set a floor on the TTL of data distributed from a zone. This floor function should be done when the data is copied into a response.

When a response is so long that truncation is required, the truncation should start at the end of the response and work forward in the datagram.

There must not be any other RRs associated with a nickname of the same class.

When data enters the domain system, its original case should be preserved whenever possible. All comparisons are done in a case-insensitive manner.

An IXFR server should keep record of the newest version of the zone and the differences between that copy and several older versions.

When a zone has been updated, it should be saved in stable storage before the new version is used. Otherwise, if the server crashes, data which is no longer available may have been distributed.

Because accuracy is essential, TCP or some other reliable protocol must be used for AXFR requests.

The AXFR protocol treats the zone contents as an unordered collection of RRs. Clients MUST accept any ordering and grouping of the non-SOA RRs.

Name compression in an AXFR message SHOULD be performed in a case-preserving manner. Although "a" equals "A" for matching, for AXFR compression "a" is not equal to "A".

Negative caching in resolvers is no longer optional. If a resolver caches anything it must also cache negative answers.

There are a large number of resolvers currently in existence that fail to correctly detect and process all forms of NXDOMAIN response.

Compute the sum of the weights, and with each RR associate the running sum. Then choose a uniform random number between 0 and the sum, and select the RR whose running sum is first which is greater than or equal to the random number.

There MUST be one or more address records for this name, the name MUST NOT be an alias.

Wildcard RRs can be thought of as instructions for synthesizing RRs. When the appropriate conditions are met, the name server creates RRs with an owner name equal to the query name.