Commit ddafe414 authored by Jim Reid's avatar Jim Reid
Browse files

Fixed some documentation errors caused by describing the aberrant behaviour of

threads in BSD/OS and mistakenly attributing that to all platforms.

Added a couple of paras on how lookups are performed.

Documented the difference n how trunctaed responses are handled.
parent 42ffd37e
......@@ -13,7 +13,7 @@
.\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
.\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.\" $Id: dig.1,v 1.1 2000/09/03 18:04:24 jim Exp $
.\" $Id: dig.1,v 1.2 2000/09/08 09:42:56 jim Exp $
.\"
.Dd Jun 30, 2000
.Dt DIG 1
......@@ -57,7 +57,7 @@ Other lookup tools tend to have less functionality than
.Nm dig .
.Pp
Although
.NM dig
.Nm dig
is normally used with command-line arguments, it also has a batch
mode of operation for reading lookup requests from a file.
A brief summary of its command-line arguments and options is printed
......@@ -69,15 +69,43 @@ Unlike earlier versions, the BIND9 implementation of
.Nm dig
allows multiple lookups to be issued from the command line.
.Pp
Unless it is told to query a specific name server,
.Nm dig
will read
.Pa /etc/resolv.conf
and send queries to the name servers identified by the
.Nm nameserver
directives in that file.
Those name servers are queried in sequence.
.Nm dig
dig will send its query to the first name server listed in
.Pa /etc/resolv.conf .
If the query times out,
.Nm dig
then tries the second name server in the list and if that query
times out, it will try the third name server.
When the query to that third name server times out,
.Nm dig
repeats the lookups.
It will try all three servers in sequence again and use a longer timeout
interval for the second series of lookup attempts.
If no answer is returned after the the second round of queries, the
lookup fails.
.Pp
The lookup completes when an answer is returned, even if that
answer indicates an error.
A commonly held misconception is that the resolver used by tools like
.Nm dig
will repeat the query to the next name server listed in
.Pa /etc/resolv.conf
if the name server that was queried returns an error reply.
This is not so.
.Pp
When no command line arguments or options are given,
.Nm dig
reads
.Pa /etc/resolv.conf
and sends a query in parallel
for details of the root zone \*q.\*q.
to each of the name servers listed in that file.
The reply from the name server that responds first is printed
and any other replies are discarded.
and makes a lookup for details of the root zone \*q.\*q
.Sh SIMPLE USAGE
.Pp
In normal usage, a typical invocation of
......@@ -103,8 +131,8 @@ argument is provided,
.Nm dig
consults
.Pa /etc/resolv.conf
and sends parallel queries to each of the name servers listed there.
The reply from the first name server to respond is displayed.
and queries the name servers listed there.
The reply from the name server that responds is displayed.
.It Ar name
is the name of the resource record that is to be looked up.
.It Ar type
......@@ -802,6 +830,18 @@ which returns the eventual answer.
.Xr RFC1035 ,
.Xr RFC2535 .
.Sh BUGS
Truncated replies are handled differently in the BIND9 implementation
of
.Nm dig .
In previous versions,
.Nm dig
would automatically repeat the query using TCP whenever it received
a truncated response.
The BIND9 implementation does not do this.
It will just display the truncated response unless
.Nm dig
was told to use a TCP connection when making queries.
.Pp
The
.Fl x
flag and
......
......@@ -13,7 +13,7 @@
.\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
.\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.\" $Id: dig.1,v 1.1 2000/09/03 18:04:24 jim Exp $
.\" $Id: dig.1,v 1.2 2000/09/08 09:42:56 jim Exp $
.\"
.Dd Jun 30, 2000
.Dt DIG 1
......@@ -57,7 +57,7 @@ Other lookup tools tend to have less functionality than
.Nm dig .
.Pp
Although
.NM dig
.Nm dig
is normally used with command-line arguments, it also has a batch
mode of operation for reading lookup requests from a file.
A brief summary of its command-line arguments and options is printed
......@@ -69,15 +69,43 @@ Unlike earlier versions, the BIND9 implementation of
.Nm dig
allows multiple lookups to be issued from the command line.
.Pp
Unless it is told to query a specific name server,
.Nm dig
will read
.Pa /etc/resolv.conf
and send queries to the name servers identified by the
.Nm nameserver
directives in that file.
Those name servers are queried in sequence.
.Nm dig
dig will send its query to the first name server listed in
.Pa /etc/resolv.conf .
If the query times out,
.Nm dig
then tries the second name server in the list and if that query
times out, it will try the third name server.
When the query to that third name server times out,
.Nm dig
repeats the lookups.
It will try all three servers in sequence again and use a longer timeout
interval for the second series of lookup attempts.
If no answer is returned after the the second round of queries, the
lookup fails.
.Pp
The lookup completes when an answer is returned, even if that
answer indicates an error.
A commonly held misconception is that the resolver used by tools like
.Nm dig
will repeat the query to the next name server listed in
.Pa /etc/resolv.conf
if the name server that was queried returns an error reply.
This is not so.
.Pp
When no command line arguments or options are given,
.Nm dig
reads
.Pa /etc/resolv.conf
and sends a query in parallel
for details of the root zone \*q.\*q.
to each of the name servers listed in that file.
The reply from the name server that responds first is printed
and any other replies are discarded.
and makes a lookup for details of the root zone \*q.\*q
.Sh SIMPLE USAGE
.Pp
In normal usage, a typical invocation of
......@@ -103,8 +131,8 @@ argument is provided,
.Nm dig
consults
.Pa /etc/resolv.conf
and sends parallel queries to each of the name servers listed there.
The reply from the first name server to respond is displayed.
and queries the name servers listed there.
The reply from the name server that responds is displayed.
.It Ar name
is the name of the resource record that is to be looked up.
.It Ar type
......@@ -802,6 +830,18 @@ which returns the eventual answer.
.Xr RFC1035 ,
.Xr RFC2535 .
.Sh BUGS
Truncated replies are handled differently in the BIND9 implementation
of
.Nm dig .
In previous versions,
.Nm dig
would automatically repeat the query using TCP whenever it received
a truncated response.
The BIND9 implementation does not do this.
It will just display the truncated response unless
.Nm dig
was told to use a TCP connection when making queries.
.Pp
The
.Fl x
flag and
......
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