262N/ACopyright (C) 2000 Internet Software Consortium.
911N/ABIND 8 to BIND 9 Migration Notes
262N/ABIND 9 is designed to be mostly upwards compatible with BIND 8, but
919N/Athere is still a number of caveats you should be aware of when
919N/Aupgrading an existing BIND 8 installation to use BIND 9.
919N/A1. Configuration File Compatibility
919N/A1.1. Unimplemented Options and Changed Defaults
919N/Aoptions of BIND 8. Unimplemented options include those for selective
919N/A(per-domain) forwarding, sortlists, statistics, and process limits;
919N/Aof these in in BIND 9.1.
919N/Awarning message. A message is also logged about each option whose
493N/AThe set of logging categories in BIND 9 is different from that
262N/Ain BIND 8. If you have customized your logging on a per-category
262N/Abasis, you need to modify your logging statement to use the
911N/AAnother difference is that the "logging" statement only takes effect
911N/Athe server starts up, any messages about errors in the configuration
911N/Afile are always logged to the default destination (syslog) when the
262N/Aserver first starts up, regardless of the contents of the "logging"
262N/Astatement. In BIND 8, the new logging configuration took effect
262N/Aimmediately after the "logging" statement was read.
493N/A2. Zone File Compatibility
262N/A2.1. Strict RFC1035 Interpretation of TTLs in Zone Files
BIND 8 allowed you to omit all TTLs from a zone file, and used the
value of the SOA MINTTL field as a default for missing TTL values.
BIND 9 enforces strict compliance with the RFC1035 and RFC2308 TTL
rules. The default TTL is the value specified with the $TTL
directive, or the previous explicit TTL if there is no $TTL directive.
If there is no $TTL directive and the first RR in the file does not
have an explicit TTL field, the error message "no TTL specified" is
logged and loading the zone file fails.
To avoid problems, use a $TTL directive in each zone file.
2.2. Periods in SOA Serial Numbers Deprecated
Some versions of BIND allow SOA serial numbers with an embedded
period, like "3.002", and convert them into integers in a rather
unintuitive way. This feature is not supported by BIND 9; serial
numbers must be integers.
2.3. Handling of Unbalanced Quotes
TXT records with unbalanced quotes, like 'host TXT "foo', were not
treated as errors in some versions of BIND. If your zone files
contain such records, you will get potentially confusing error
messages like "unexpected end of file" because BIND 9 will interpret
everything up to the next quote character as a literal string.
3. Interoperability Impact of New Protocol Features
BIND 9 uses EDNS0 (RFC2671) to advertise its receive buffer size. It
also sets the AD bit in queries to indicate that it wishes to receive
DNSSEC responses (this usage of the AD bit is not yet standard, but
hopefully it will be soon).
Most older servers that do not support EDNS0
and/or DNSSEC, including
all known versions of BIND, will send a FORMERR or NOTIMP response to
these queries. When this happens, BIND 9 will automatically retry the
query without EDNS0 and AD.
Unfortunately, there exists at least one non-BIND name server
implementation that silently ignores these queries instead of sending
an error response. Resolving names in zones where all or most
authoritative servers use this server will be very slow or fail
completely. We have contacted the manufacturer of the name server in
case and are trying to resolve the issue with them.
$Id: migration,v 1.3 2000/07/14 17:11:07 gson Exp $