serial number
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... 1035std13, and is believed to generally agree with current
implementations. However, older, superseded, implementations are
known to have treated the serial number as a simple unsigned integer,
with no attempt to implement any kind of "sequence space arithmetic",
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... Serial Number Arithmetic ...
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Serial numbers are formed from non-negative integers from a finite
subset of the range of all integer values ...
...
When considered as serial numbers however no value has any particular
significance, there is no minimum or maximum serial number, every
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... When considered as serial numbers however no value has any particular
significance, there is no minimum or maximum serial number, every
value has a successor and predecessor.
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...
To define a serial number to be used in this way, the size of the
serial number space must be given. This value, called "SERIAL_BITS ...
... To define a serial number to be used in this way, the size of the
serial number space must be given. This value, called "SERIAL_BITS",
gives the power of two which results in one larger than the largest
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... gives the power of two which results in one larger than the largest
integer corresponding to a serial number value. This also specifies
the number of bits required to hold every possible value of a serial
number ...
... serial number value. This also specifies
the number of bits required to hold every possible value of a serial
number of the defined type. The operations permitted upon serial
numbers are defined in the following section.
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... the number of bits required to hold every possible value of a serial
number of the defined type. The operations permitted upon serial
numbers are defined in the following section.
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... Operations upon the serial number ...
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Only two operations are defined upon serial numbers, addition of a
positive integer of limited range ...
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Serial numbers may be incremented by the addition of a positive
integer n, where n is taken from the range ...
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Any two serial numbers, s1 and s2, may be compared. The definition
of the result of this comparison is as follows.
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...
The simplest meaningful serial number space has SERIAL_BITS == 2. In
this space, the integers that make up the serial number ...
... serial number space has SERIAL_BITS == 2. In
this space, the integers that make up the serial number space are 0,
1, 2, and 3. That is, 3 == 2^SERIAL_BITS - 1.
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... Consider the case where SERIAL_BITS == 8. In this space the integers
that make up the serial number space are 0, 1, 2, ... 254, 255.
255 == 2^SERIAL_BITS - 1.
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...
Note that 100+100 > 100, but that (100+100)+100 < 100. Incrementing
a serial number can cause it to become "smaller". Of course,
incrementing by a smaller number will allow many more increments to
be made before this occurs. However this is always something to be
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... be made before this occurs. However this is always something to be
aware of, it can cause surprising errors, or be useful as it is the
only defined way to actually cause a serial number to decrease.
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... As this defined arithmetic may be useful for purposes other than for
the DNS serial number, it may be referenced as Serial Number
Arithmetic from RFC1982prop ...
... the DNS serial number, it may be referenced as Serial Number
Arithmetic from RFC1982prop. Any such reference shall be taken as
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... The DNS SOA serial number ...
... serial number in the DNS SOA Resource Record is a Serial Number
as defined above, with SERIAL_BITS being 32. That is, the serial
number ...
... Serial Number
as defined above, with SERIAL_BITS being 32. That is, the serial
number is a non negative integer with values taken from the range
...
...
Care should be taken that the serial number not be incremented, in
one or more steps, by more than this maximum within the period given
by the value of SOA.expire. Doing so may leave some secondary
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... one or more steps, by more than this maximum within the period given
by the value of SOA.expire. Doing so may leave some secondary
servers with out of date copies of the zone, but with a serial number
"greater" than that of the primary server. Of course, special
circumstances may require this rule be set aside, for example, when
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... "greater" than that of the primary server. Of course, special
circumstances may require this rule be set aside, for example, when
the serial number needs to be set lower for some reason. If this
must be done, then take special care to verify that ALL servers have
correctly succeeded in following the primary server's serial number ...
... serial number needs to be set lower for some reason. If this
must be done, then take special care to verify that ALL servers have
correctly succeeded in following the primary server's serial number
changes, at each step.
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...
Note that each, and every, increment to the serial number must be
treated as the start of a new sequence of increments for this
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...
Caution should also be exercised before causing the serial number to
be set to the value zero. While this value is not in any way special
in serial number ...
... serial number to
be set to the value zero. While this value is not in any way special
in serial number arithmetic, or to the DNS SOA serial number, many
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... in serial number arithmetic, or to the DNS SOA serial number, many
DNS implementations have incorrectly treated zero as a special case,
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... with special properties, and unusual behaviour may be expected if
zero is used as a DNS SOA serial number.
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... 1035std13 are to be treated as if the references to
"sequence space arithmetic" therein are replaced by references to
serial number arithmetic, as defined in this document.
...