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		   BIND 4 to BIND 9 Migration Notes

To transition from BIND 4 to BIND 9 you first need to convert your
configuration file to the new format.  There is a conversion tool in
contrib/named-bootconf that allows you to do this.

	named-bootconf.sh < /etc/named.boot > /etc/named.conf

BIND 9 uses a system assigned port for the UDP queries it makes rather
than port 53 that BIND 4 uses.  This may conflict with some firewalls.
The following directives in /etc/named.conf allows you to specify
a port to use.

	query-source address * port 53;
	transfer-source * port 53;
	notify-source * port 53;

BIND 9 no longer uses the minimum field to specify the TTL of records
without a explicit TTL.  Use the $TTL directive to specify a default TTL
before the first record without a explicit TTL.

	$TTL 3600
	@	IN	SOA	ns1.example.com. hostmaster.example.com. (
				2001021100
				7200
				1200
				3600000
				7200 )

BIND 9 does not support multiple CNAMEs with the same owner name.
	
	Illegal:
	www.example.com. CNAME host1.example.com.
	www.example.com. CNAME host2.example.com.

BIND 9 does not support "CNAMEs with other data" with the same owner name,
ignoring the DNSSEC records (SIG, NXT, KEY) that BIND 4 did not support.

	Illegal:
	www.example.com. CNAME host1.example.com.
	www.example.com. MX 10 host2.example.com.

BIND 9 is less tolerant of errors in master files, so check your logs and
fix any errors reported.  The named-checkzone program can also be to check
master files.

Outgoing zone transfers now use the "many-answers" format by default.
This format is not understood by certain old versions of BIND 4.  
You can work around this problem using the option "transfer-format
one-answer;", but since these old versions all have known security
problems, the correct fix is to upgrade the slave servers.