NAME
axfr-get - a DNS zone-transfer client.
It sends a zone-transfer request in DNS-over-TCP format to descriptor
7, reads the results from descriptor 6, and saves the results in a
file.
SYNOPSIS
Normally axfr-get is run under tcpclient(1), which sets up descriptors
6 and 7 as a TCP connection to a remote host.
axfr-get z fn fn.tmp
DESCRIPTION
axfr-get performs a zone transfer for domain z. It writes the results
to fn.tmp in a format that can be used as input to tinydns-data(8). If
the zone transfer completes successfully, axfr-get atomically renames
fn.tmp as fn.
fn.tmp and fn must be on the same filesystem.
axfr-get writes the zone serial number as a comment at the top of
fn.tmp. It skips the zone transfer, leaving fn alone, if fn already
exists,
fn has a serial number matching the zone serial number, and both serial
numbers are nonzero.
Zone transfers often include duplicate records. You should feed the
axfr-get results through sort -u.
axfr-get discards all records outside the domain z. It accepts records
in child zones, but it marks all child zones as non-authoritative, so
tinydns(8) will not report those records except as glue. If you plan
to merge the axfr-get results for a domain and a child of the same
domain, creating a file authoritative for both zones, make sure to
eliminate records in the first output that are within the child zone.
axfr-get will accept arbitrarily large zone transfers. To limit the
maximum file size to 1 megabyte, run axfr-get under softlimit -f
1048576.
Compatibility notes
axfr-get handles BIND’s RFC-1034-violating multiple-answers zone-
transfer format.
axfr-get does not precisely simulate BIND’s handling of *.dom. Under
BIND, records for *.dom do not apply to y.dom or anything.y.dom if
there is a normal record for x.y.dom. With axfr-get and tinydns(8),
the records apply to y.dom and anything.y.dom except x.y.dom.
axfr-get does not precisely simulate BIND’s handling of multiple IP
addresses for a single name. When there are more than 8 addresses,
tinydns(8) selects a random set of 8 for each query.
SEE ALSO
axfrdns(8), tinydns(8), tinydns-data(8), tcpclient(1), softlimit(8)
http://cr.yp.to/djbdns.html
axfr-get(8)