0N/ACopyright (C) 2000 Internet Software Consortium.
0N/A BIND 8 to BIND 9 Migration Notes
0N/ABIND 9 is designed to be mostly upwards compatible with BIND 8, but
0N/Athere is still a number of caveats you should be aware of when
0N/Aupgrading an existing BIND 8 installation to use BIND 9.
0N/A1. Configuration File Compatibility
0N/A1.1. Unimplemented Options and Changed Defaults
0N/Aoptions of BIND 8. Unimplemented options include those for selective
0N/A(per-domain) forwarding, sortlists, statistics, and process limits;
0N/Aof these in in BIND 9.1.
0N/AIf your
named.conf file uses an unimplemented option, named will log a
0N/Awarning message. A message is also logged about each option whose
0N/A1.2. Handling of Configuration File Errors
0N/AIn BIND 9, named refuses to start if it detects an error in
0N/Aserver to run with a partial configuration. Errors detected during
0N/Asubsequent reloads do not cause the server to exit.
0N/AThe set of logging categories in BIND 9 is different from that
0N/Ain BIND 8. If you have customized your logging on a per-category
0N/Abasis, you need to modify your logging statement to use the
0N/AAnother difference is that the "logging" statement only takes effect
0N/Aafter the entire
named.conf file has been read. This means that when
0N/Athe server starts up, any messages about errors in the configuration
0N/Afile are always logged to the default destination (syslog) when the
0N/Aserver first starts up, regardless of the contents of the "logging"
0N/Astatement. In BIND 8, the new logging configuration took effect
0N/Aimmediately after the "logging" statement was read.
0N/A1.4. Case sensitivity
0N/AIn BIND 9, ACL names are case sensitive. In BIND 8 they were case
0N/A2. Zone File Compatibility
0N/A2.1. Strict RFC1035 Interpretation of TTLs in Zone Files
0N/ABIND 8 allowed you to omit all TTLs from a zone file, and used the
0N/Avalue of the SOA MINTTL field as a default for missing TTL values.
0N/ABIND 9 enforces strict compliance with the RFC1035 and RFC2308 TTL
0N/Arules. The default TTL is the value specified with the $TTL
0N/Adirective, or the previous explicit TTL if there is no $TTL directive.
0N/AIf there is no $TTL directive and the first RR in the file does not
0N/Ahave an explicit TTL field, the error message "no TTL specified" is
0N/Alogged and loading the zone file fails.
0N/ATo avoid problems, use a $TTL directive in each zone file.
0N/A2.2. Periods in SOA Serial Numbers Deprecated
0N/ASome versions of BIND allow SOA serial numbers with an embedded
0N/Aperiod, like "3.002", and convert them into integers in a rather
0N/Aunintuitive way. This feature is not supported by BIND 9; serial
0N/Anumbers must be integers.
0N/A2.3. Handling of Unbalanced Quotes
0N/ATXT records with unbalanced quotes, like 'host TXT "foo', were not
0N/Atreated as errors in some versions of BIND. If your zone files
0N/Acontain such records, you will get potentially confusing error
0N/Amessages like "unexpected end of file" because BIND 9 will interpret
0N/Aeverything up to the next quote character as a literal string.
0N/A2.4. Handling of Line Breaks
Some versions of BIND accept RRs containing line breaks that are not
properly quoted with parentheses, like the following SOA:
( 1 3600 1800 1814400 3600 )
This is not legal master file syntax and will be treated as an error
by BIND 9. The fix is to move the opening parenthesis to the first
2.5. Unimplemented BIND 8 Extensions
$GENERATE: This deprecated form of getting a literal $ into a domain
name ($$) is no longer supported, use \$ instead.
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.
4. Unrestricted Character Set
BIND 9 does not restrict the character set of domain names - it is
fully 8-bit clean in accordance with RFC2181 section 11.
It is strongly recommended that hostnames published in the DNS follow
the RFC952 rules, but BIND 9 will not enforce this restriction.
Historically, some applications have suffered from security flaws
where data originating from the network, such as names returned by
gethostbyaddr(), are used with insufficient checking and may cause a
breach of security when containing unexpected characters; see
for details. Some earlier versions of BIND attempt to protect these
flawed applications from attack by discarding data containing
characters deemed inappropriate in host names or mail addresses, under
no-check-names" in
resolv.conf. BIND 9 provides no such protection;
if applications with these flaws are still being used, they should
5. Server Administration Tools
The "ndc" program has been replaced by "rndc", which is capable of
remote operation. Unlike ndc, rndc requires a configuration file;
details. Many of the ndc commands are still unimplemented in rndc.
$Id: migration,v 1.13 2000/09/18 06:50:35 marka Exp $