@ -358,7 +358,7 @@ should never happen.
|
|||||||
|
|
||||||
## Zone files
|
## Zone files
|
||||||
Zone files are one way of storing DNS data, but these are not integral to
|
Zone files are one way of storing DNS data, but these are not integral to
|
||||||
the operation of a nameserver. The zone file format is standardised, but it
|
the operation of a nameserver. The zone file format is standardized, but it
|
||||||
is highly non-trivial to parse. It is entirely possible to write useful
|
is highly non-trivial to parse. It is entirely possible to write useful
|
||||||
nameserver that does not read or write DNS zone files. When embarking on
|
nameserver that does not read or write DNS zone files. When embarking on
|
||||||
parsing zonefiles, do not do so lightly. As an example, various fields
|
parsing zonefiles, do not do so lightly. As an example, various fields
|
||||||
@ -614,7 +614,7 @@ record is created on the fly.
|
|||||||
## Truncation
|
## Truncation
|
||||||
Without implementing the optional EDNS protocol extension, all UDP responses
|
Without implementing the optional EDNS protocol extension, all UDP responses
|
||||||
must fit in 512 bytes of payload. If on writing an answer a server finds
|
must fit in 512 bytes of payload. If on writing an answer a server finds
|
||||||
itself exceding this limit, it must truncate the packet and set the TC bit
|
itself exceeding this limit, it must truncate the packet and set the TC bit
|
||||||
to 1.
|
to 1.
|
||||||
|
|
||||||
The originator of the query will then resend the query over TCP.
|
The originator of the query will then resend the query over TCP.
|
||||||
|
2
meta.md
2
meta.md
@ -6,7 +6,7 @@ There are now between 1500 and 3000 pages of RFC documents describing DNS,
|
|||||||
containing around 1700 'MUST' statements.
|
containing around 1700 'MUST' statements.
|
||||||
|
|
||||||
Not only are there a lot of documents, the earlier ones are not that easy to
|
Not only are there a lot of documents, the earlier ones are not that easy to
|
||||||
read for newcomers, and contain a lot of obsoleted bagage that new readers
|
read for newcomers, and contain a lot of obsoleted baggage that new readers
|
||||||
do not know they can skip.
|
do not know they can skip.
|
||||||
|
|
||||||
Inspired by the wonderful books by W. Richard Stevens (like [TCP
|
Inspired by the wonderful books by W. Richard Stevens (like [TCP
|
||||||
|
2
stub.md
2
stub.md
@ -19,7 +19,7 @@ resolver a stub talks to should take care of everything.
|
|||||||
XXX - where does it say so?
|
XXX - where does it say so?
|
||||||
|
|
||||||
A few things do matter. For security purposes, the stub resolver must take
|
A few things do matter. For security purposes, the stub resolver must take
|
||||||
good care to fully randomise source port and ID fields. It must also guard
|
good care to fully randomize source port and ID fields. It must also guard
|
||||||
against sending out multiple equivalent queries at the same time as this
|
against sending out multiple equivalent queries at the same time as this
|
||||||
would allow a 'birthday attack' that could spoof in harmful answers.
|
would allow a 'birthday attack' that could spoof in harmful answers.
|
||||||
|
|
||||||
|
Reference in New Issue
Block a user