Technical data

Configuring and Managing BIND
5.3 Configuring the BIND Server (BIND 8.1)
• Scans the transaction log file once per hour and updates the domain_name.DB
file with any transactions it finds by writing a new version of the domain_
name.DB file to disk. This action does not preserve the formatting
or comments that existed in the original domain_name.DB file. (See
Section 5.3.6.1 for solutions for preserving the formatting or comments in
the original domain_name.DB file.)
• Renames the current transaction log file to domain_name.DB_LOG_BCK and
then creates a new domain_name.DB_LOG file.
5.3.6.1 Preserving the Zone File
Typically, a system administrator adds comments to the domain_name.DB file
to provide history and helpful information pertinent to the data in the file,
and formats the file for easy reading. With DNS dynamic updates enabled, all
comments, formatting, and ordering will be lost.
TCP/IP Services provides two methods to prevent this:
You can use the DCL command DEFINE to define the logical
TCPIP$BIND_DONT_MERGE_DYNAMIC_UPDATES. The presence of the
logical turns off the merge of dynamic updates, and the server does not create
new versions of the domain_name.DB.
TCP/IP Services BIND server preserves the original domain_name.DB file
that is read when the BIND server starts up. The server never deletes or
purges the original database file.
The BIND server is able to detect a situation in which dynamic updates
might be lost. When this happens, the server creates a new version of the
domain_name.DB_LOG_BCK file containing the dynamic updates that would
have been lost. The system administrator must review the transactions in the file
and determine whether the updates are still valid and if so, manually apply the
updates to the domain_name.DB file.
There is always at least one version of the domain_name.DB_LOG_BCK file when
dynamic updates are enabled. Each time the BIND server detects lost updates,
the server creates a new version of the domain_name.DB_LOG_BCK file. The
existence of more than one of these files is a signal to the system administrator
that manual merges may be necessary.
The server does not automatically purge the domain_name.DB_LOG_BCK files,
but the system administrator can delete them after examining and applying their
contents.
5.3.6.2 Manually Creating Updates
You can manually create updates to the domain database file using the command
line utility
NSUPDATE if the name server for the domain is configured to accept
dynamic updates.
The format of the NSUPDATE command is:
NSUPDATE [ -d ] [ -v ] [ file-name ]
In this format:
-d Specifies debug mode.
-v Specifies that NSUPDATE uses the TCP protocol instead of the UDP
protocol.
file-name Specifies a file name containing update requests and entries.
Configuring and Managing BIND 5–21