DNS Configuration and Management Manual (G06.27+, H06.05+, J06.03+)

BIND 9.x on the NonStop Server
HP DNS Configuration and Management Manual—529432-003
2-9
Incremental Zone Transfer (IXFR)
3. Run the rndc command:
This command results in a connection to the 127.0.0.1 port 953 and reloads the
name server.
Example: Using rndc to Stop the Name Server
In the following example, rndc stops the name server running on 10.53.0.1.
The communication between the name server and rndc is secured by a shared secret
key. rndc reads the rndc configuration file to determine how to contact the name server
and decide what algorithm and key to use.
For more information, see the rndc man pages in OSS. (For help locating the man
page, see Table 2-1, OSS Commands to Access man Pages, on page 2-3.)
Incremental Zone Transfer (IXFR)
Incremental zone transfer is a mechanism for slave servers to transfer only the
changed data instead of transferring the entire zone data every time the zone data
changes. RFC 1995, “Incremental Zone Transfer in DNS introduced Incremental Zone
Transfers (IXFR)” describes this tool. IXFR is set to ON by default.
Slave servers inform master servers about the version of a zone they currently hold
and request just the changes to the zone between the version they have and the
current version. This arrangement dramatically reduces the size and duration of a zone
transfer. Transferring very large zone files can take a long time and waste bandwidth
and other resources, especially if only a single record has been changed.
An incremental zone-transfer request has a query type of IXFR instead of AXFR (the
type of query that initiates a full zone transfer), and it contains the slave's current start
of authority (SOA) record from the zone in the authority section of the message.
Incremental zone transfers are always carried out using TCP on port 53 not UDP.
(Normal DNS query operations use UDP on port 53.)
When the master name server receives an incremental zone-transfer request, it looks
for the record of the changes to the zone between the slave's version of the zone and
the version the master holds. If that record is missing, the master sends a full zone
transfer. Otherwise, it sends just the differences between the versions of the zone.
When acting as a slave server, BIND attempts to use IXFR unless incremental zone
transfer is explicitly disabled.
$ rndc -c /etc/dns_secure/rndc.conf reload
Example 2-2. rndc Command
> rndc -c /etc/dns_secure/rndc.conf -s 10.53.0.1 stop
Note. IXFR works best if you use dynamic updates to modify your zone files.