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<article class="faq">

<title>Frequently Asked Questions about BIND 9</title>

<articleinfo>

<copyright>

<year>2004</year>

<year>2005</year>

<year>2006</year>

<year>2007</year>

<year>2008</year>

<year>2009</year>

<year>2010</year>

<year>2012</year>

<year>2013</year>

<holder>Internet Systems Consortium, Inc. ("ISC")</holder>

</copyright>

<copyright>

<year>2000</year>

<year>2001</year>

<year>2002</year>

<year>2003</year>

<holder>Internet Software Consortium.</holder>

</copyright>

</articleinfo>

<qandaset defaultlabel='qanda'>

<qandadiv><title>Compilation and Installation Questions</title>

<qandaentry>

<question>

<para>

I'm trying to compile BIND 9, and "make" is failing due to

files not being found. Why?

</para>

</question>

<answer>

<para>

Using a parallel or distributed "make" to build BIND 9 is

not supported, and doesn't work. If you are using one of

these, use normal make or gmake instead.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Isn't "make install" supposed to generate a default named.conf?

</para>

</question>

<answer>

<para>

Short Answer: No.

</para>

<para>

Long Answer: There really isn't a default configuration which fits

any site perfectly. There are lots of decisions that need to

be made and there is no consensus on what the defaults should be.

For example FreeBSD uses /etc/namedb as the location where the

configuration files for named are stored. Others use /var/named.

</para>

<para>

What addresses to listen on? For a laptop on the move a lot

you may only want to listen on the loop back interfaces.

</para>

<para>

Who do you offer recursive service to? Is there are firewall

to consider? If so is it stateless or stateful. Are you

directly on the Internet? Are you on a private network? Are

you on a NAT'd network? The answers

to all these questions change how you configure even a

caching name server.

</para>

</answer>

</qandaentry>

</qandadiv> <!-- Compilation and Installation Questions -->

<qandadiv><title>Configuration and Setup Questions</title>

<qandaentry>

<!-- configuration, log -->

<question>

<para>

Why does named log the warning message <quote>no TTL specified -

using SOA MINTTL instead</quote>?

</para>

</question>

<answer>

<para>

Your zone file is illegal according to RFC1035. It must either

have a line like:

</para>

<informalexample>

<programlisting>

$TTL 86400</programlisting>

</informalexample>

<para>

at the beginning, or the first record in it must have a TTL field,

like the "84600" in this example:

</para>

<informalexample>

<programlisting>

example.com. 86400 IN SOA ns hostmaster ( 1 3600 1800 1814400 3600 )</programlisting>

</informalexample>

</answer>

</qandaentry>

<qandaentry>

<!-- configuration -->

<question>

<para>

Why do I get errors like <quote>dns_zone_load: zone foo/IN: loading

master file bar: ran out of space</quote>?

</para>

</question>

<answer>

<para>

This is often caused by TXT records with missing close

quotes. Check that all TXT records containing quoted strings

have both open and close quotes.

</para>

</answer>

</qandaentry>

<qandaentry>

<!-- security -->

<question>

<para>

How do I restrict people from looking up the server version?

</para>

</question>

<answer>

<para>

Put a "version" option containing something other than the

real version in the "options" section of named.conf. Note

doing this will not prevent attacks and may impede people

trying to diagnose problems with your server. Also it is

possible to "fingerprint" nameservers to determine their

version.

</para>

</answer>

</qandaentry>

<qandaentry>

<!-- security -->

<question>

<para>

How do I restrict only remote users from looking up the

server version?

</para>

</question>

<answer>

<para>

The following view statement will intercept lookups as the

internal view that holds the version information will be

matched last. The caveats of the previous answer still

apply, of course.

</para>

<informalexample>

<programlisting>

view "chaos" chaos {

match-clients { &lt;those to be refused&gt;; };

allow-query { none; };

zone "." {

type hint;

file "/dev/null"; // or any empty file

};

};</programlisting>

</informalexample>

</answer>

</qandaentry>

<qandaentry>

<!-- configuration -->

<question>

<para>

What do <quote>no source of entropy found</quote> or <quote>could not

open entropy source foo</quote> mean?

</para>

</question>

<answer>

<para>

The server requires a source of entropy to perform certain

operations, mostly DNSSEC related. These messages indicate

that you have no source of entropy. On systems with

/dev/random or an equivalent, it is used by default. A

source of entropy can also be defined using the random-device

option in named.conf.

</para>

</answer>

</qandaentry>

<qandaentry>

<!-- configuration -->

<question>

<para>

I'm trying to use TSIG to authenticate dynamic updates or

zone transfers. I'm sure I have the keys set up correctly,

but the server is rejecting the TSIG. Why?

</para>

</question>

<answer>

<para>

This may be a clock skew problem. Check that the the clocks

on the client and server are properly synchronised (e.g.,

using ntp).

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I see a log message like the following. Why?

</para>

<para>

couldn't open pid file '/var/run/named.pid': Permission denied

</para>

</question>

<answer>

<para>

You are most likely running named as a non-root user, and

that user does not have permission to write in /var/run.

The common ways of fixing this are to create a /var/run/named

directory owned by the named user and set pid-file to

"/var/run/named/named.pid", or set pid-file to "named.pid",

which will put the file in the directory specified by the

directory option (which, in this case, must be writable by

the named user).

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I can query the nameserver from the nameserver but not from other

machines. Why?

</para>

</question>

<answer>

<para>

This is usually the result of the firewall configuration stopping

the queries and / or the replies.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

How can I make a server a slave for both an internal and

an external view at the same time? When I tried, both views

on the slave were transferred from the same view on the master.

</para>

</question>

<answer>

<para>

You will need to give the master and slave multiple IP

addresses and use those to make sure you reach the correct

view on the other machine.

</para>

<informalexample>

<programlisting>

Master: 10.0.1.1 (internal), 10.0.1.2 (external, IP alias)

internal:

match-clients { !10.0.1.2; !10.0.1.4; 10.0.1/24; };

notify-source 10.0.1.1;

transfer-source 10.0.1.1;

query-source address 10.0.1.1;

external:

match-clients { any; };

recursion no; // don't offer recursion to the world

notify-source 10.0.1.2;

transfer-source 10.0.1.2;

query-source address 10.0.1.2;

Slave: 10.0.1.3 (internal), 10.0.1.4 (external, IP alias)

internal:

match-clients { !10.0.1.2; !10.0.1.4; 10.0.1/24; };

notify-source 10.0.1.3;

transfer-source 10.0.1.3;

query-source address 10.0.1.3;

external:

match-clients { any; };

recursion no; // don't offer recursion to the world

notify-source 10.0.1.4;

transfer-source 10.0.1.4;

query-source address 10.0.1.4;</programlisting>

</informalexample>

<para>

You put the external address on the alias so that all the other

dns clients on these boxes see the internal view by default.

</para>

</answer>

<answer>

<para>

BIND 9.3 and later: Use TSIG to select the appropriate view.

</para>

<informalexample>

<programlisting>

Master 10.0.1.1:

key "external" {

algorithm hmac-sha256;

secret "xxxxxxxxxxxxxxxxxxxxxxxx";

};

view "internal" {

match-clients { !key external; // reject message ment for the

// external view.

10.0.1/24; }; // accept from these addresses.

...

};

view "external" {

match-clients { key external; any; };

server 10.0.1.2 { keys external; }; // tag messages from the

// external view to the

// other servers for the

// view.

recursion no;

...

};

Slave 10.0.1.2:

key "external" {

algorithm hmac-sha256;

secret "xxxxxxxxxxxxxxxxxxxxxxxx";

};

view "internal" {

match-clients { !key external; 10.0.1/24; };

...

};

view "external" {

match-clients { key external; any; };

server 10.0.1.1 { keys external; };

recursion no;

...

};</programlisting>

</informalexample>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I get error messages like <quote>multiple RRs of singleton type</quote>

and <quote>CNAME and other data</quote> when transferring a zone. What

does this mean?

</para>

</question>

<answer>

<para>

These indicate a malformed master zone. You can identify

the exact records involved by transferring the zone using

dig then running named-checkzone on it.

</para>

<informalexample>

<programlisting>

dig axfr example.com @master-server &gt; tmp

named-checkzone example.com tmp</programlisting>

</informalexample>

<para>

A CNAME record cannot exist with the same name as another record

except for the DNSSEC records which prove its existence (NSEC).

</para>

<para>

RFC 1034, Section 3.6.2: <quote>If a CNAME RR is present at a node,

no other data should be present; this ensures that the data for a

canonical name and its aliases cannot be different. This rule also

insures that a cached CNAME can be used without checking with an

authoritative server for other RR types.</quote>

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I get error messages like <quote>named.conf:99: unexpected end

of input</quote> where 99 is the last line of named.conf.

</para>

</question>

<answer>

<para>

There are unbalanced quotes in named.conf.

</para>

</answer>

<answer>

<para>

Some text editors (notepad and wordpad) fail to put a line

title indication (e.g. CR/LF) on the last line of a

text file. This can be fixed by "adding" a blank line to

the end of the file. Named expects to see EOF immediately

after EOL and treats text files where this is not met as

truncated.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

How do I share a dynamic zone between multiple views?

</para>

</question>

<answer>

<para>

You choose one view to be master and the second a slave and

transfer the zone between views.

</para>

<informalexample>

<programlisting>

Master 10.0.1.1:

key "external" {

algorithm hmac-sha256;

secret "xxxxxxxxxxxxxxxxxxxxxxxx";

};

key "mykey" {

algorithm hmac-sha256;

secret "yyyyyyyyyyyyyyyyyyyyyyyy";

};

view "internal" {

match-clients { !key external; 10.0.1/24; };

server 10.0.1.1 {

/* Deliver notify messages to external view. */

keys { external; };

};

zone "example.com" {

type master;

file "internal/example.db";

allow-update { key mykey; };

also-notify { 10.0.1.1; };

};

};

view "external" {

match-clients { key external; any; };

zone "example.com" {

type slave;

file "external/example.db";

masters { 10.0.1.1; };

transfer-source 10.0.1.1;

// allow-update-forwarding { any; };

// allow-notify { ... };

};

};</programlisting>

</informalexample>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I get a error message like <quote>zone wireless.ietf56.ietf.org/IN:

loading master file primaries/wireless.ietf56.ietf.org: no

owner</quote>.

</para>

</question>

<answer>

<para>

This error is produced when a line in the master file

contains leading white space (tab/space) but the is no

current record owner name to inherit the name from. Usually

this is the result of putting white space before a comment,

forgetting the "@" for the SOA record, or indenting the master

file.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Why are my logs in GMT (UTC).

</para>

</question>

<answer>

<para>

You are running chrooted (-t) and have not supplied local timezone

information in the chroot area.

</para>

<simplelist>

<member>FreeBSD: /etc/localtime</member>

<member>Solaris: /etc/TIMEZONE and /usr/share/lib/zoneinfo</member>

<member>OSF: /etc/zoneinfo/localtime</member>

</simplelist>

<para>

See also tzset(3) and zic(8).

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I get <quote>rndc: connect failed: connection refused</quote> when

I try to run rndc.

</para>

</question>

<answer>

<para>

This is usually a configuration error.

</para>

<para>

First ensure that named is running and no errors are being

reported at startup (/var/log/messages or equivalent).

Running "named -g &lt;usual arguments&gt;" from a title

can help at this point.

</para>

<para>

Secondly ensure that named is configured to use rndc either

by "rndc-confgen -a", rndc-confgen or manually. The

Administrators Reference manual has details on how to do

this.

</para>

<para>

Old versions of rndc-confgen used localhost rather than

127.0.0.1 in /etc/rndc.conf for the default server. Update

/etc/rndc.conf if necessary so that the default server

listed in /etc/rndc.conf matches the addresses used in

named.conf. "localhost" has two address (127.0.0.1 and

::1).

</para>

<para>

If you use "rndc-confgen -a" and named is running with -t or -u

ensure that /etc/rndc.conf has the correct ownership and that

a copy is in the chroot area. You can do this by re-running

"rndc-confgen -a" with appropriate -t and -u arguments.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I get <quote>transfer of 'example.net/IN' from 192.168.4.12#53:

failed while receiving responses: permission denied</quote> error

messages.

</para>

</question>

<answer>

<para>

These indicate a filesystem permission error preventing

named creating / renaming the temporary file. These will

usually also have other associated error messages like

</para>

<informalexample>

<programlisting>

"dumping master file: sl/tmp-XXXX5il3sQ: open: permission denied"</programlisting>

</informalexample>

<para>

Named needs write permission on the directory containing

the file. Named writes the new cache file to a temporary

file then renames it to the name specified in named.conf

to ensure that the contents are always complete. This is

to prevent named loading a partial zone in the event of

power failure or similar interrupting the write of the

master file.

</para>

<para>

Note file names are relative to the directory specified in

options and any chroot directory ([&lt;chroot

dir&gt;/][&lt;options dir&gt;]).

</para>

<informalexample>

<para>

If named is invoked as "named -t /chroot/DNS" with

the following named.conf then "/chroot/DNS/var/named/sl"

needs to be writable by the user named is running as.

</para>

<programlisting>

options {

directory "/var/named";

};

zone "example.net" {

type slave;

file "sl/example.net";

masters { 192.168.4.12; };

};</programlisting>

</informalexample>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I want to forward all DNS queries from my caching nameserver to

another server. But there are some domains which have to be

served locally, via rbldnsd.

</para>

<para>

How do I achieve this ?

</para>

</question>

<answer>

<programlisting>

options {

forward only;

forwarders { &lt;ip.of.primary.nameserver&gt;; };

};

zone "sbl-xbl.spamhaus.org" {

type forward; forward only;

forwarders { &lt;ip.of.rbldns.server&gt; port 530; };

};

zone "list.dsbl.org" {

type forward; forward only;

forwarders { &lt;ip.of.rbldns.server&gt; port 530; };

};

</programlisting>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Can you help me understand how BIND 9 uses memory to store

DNS zones?

</para>

<para>

Some times it seems to take several times the amount of

memory it needs to store the zone.

</para>

</question>

<answer>

<para>

When reloading a zone named my have multiple copies of

the zone in memory at one time. The zone it is serving

and the one it is loading. If reloads are ultra fast it

can have more still.

</para>

<para>

e.g. Ones that are transferring out, the one that it is

serving and the one that is loading.

</para>

<para>

BIND 8 destroyed the zone before loading and also killed

off outgoing transfers of the zone.

</para>

<para>

The new strategy allows slaves to get copies of the new

zone regardless of how often the master is loaded compared

to the transfer time. The slave might skip some intermediate

versions but the transfers will complete and it will keep

reasonably in sync with the master.

</para>

<para>

The new strategy also allows the master to recover from

syntax and other errors in the master file as it still

has an in-core copy of the old contents.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I want to use IPv6 locally but I don't have a external IPv6

connection. External lookups are slow.

</para>

</question>

<answer>

<para>

You can use server clauses to stop named making external lookups

over IPv6.

</para>

<programlisting>

server fd81:ec6c:bd62::/48 { bogus no; }; // site ULA prefix

server ::/0 { bogus yes; };

</programlisting>

</answer>

</qandaentry>

</qandadiv> <!-- Configuration and Setup Questions -->

<qandadiv><title>Operations Questions</title>

<qandaentry>

<question>

<para>

How to change the nameservers for a zone?

</para>

</question>

<answer>

<para>

Step 1: Ensure all nameservers, new and old, are serving the

same zone content.

</para>

<para>

Step 2: Work out the maximum TTL of the NS RRset in the parent and child

zones. This is the time it will take caches to be clear of a

particular version of the NS RRset.

If you are just removing nameservers you can skip to Step 6.

</para>

<para>

Step 3: Add new nameservers to the NS RRset for the zone and

wait until all the servers for the zone are answering with this

new NS RRset.

</para>

<para>

Step 4: Inform the parent zone of the new NS RRset then wait for all the

parent servers to be answering with the new NS RRset.

</para>

<para>

Step 5: Wait for cache to be clear of the old NS RRset.

See Step 2 for how long.

If you are just adding nameservers you are done.

</para>

<para>

Step 6: Remove any old nameservers from the zones NS RRset and

wait for all the servers for the zone to be serving the new NS RRset.

</para>

<para>

Step 7: Inform the parent zone of the new NS RRset then wait for all the

parent servers to be answering with the new NS RRset.

</para>

<para>

Step 8: Wait for cache to be clear of the old NS RRset.

See Step 2 for how long.

</para>

<para>

Step 9: Turn off the old nameservers or remove the zone entry from

the configuration of the old nameservers.

</para>

<para>

Step 10: Increment the serial number and wait for the change to

be visible in all nameservers for the zone. This ensures that

zone transfers are still working after the old servers are

decommissioned.

</para>

<para>

Note: the above procedure is designed to be transparent

to dns clients. Decommissioning the old servers too early

will result in some clients not being able to look up

answers in the zone.

</para>

<para>

Note: while it is possible to run the addition and removal

stages together it is not recommended.

</para>

</answer>

</qandaentry>

</qandadiv> <!-- Operations Questions -->

<qandadiv><title>General Questions</title>

<qandaentry>

<question>

<para>

I keep getting log messages like the following. Why?

</para>

<para>

Dec 4 23:47:59 client 10.0.0.1#1355: updating zone

'example.com/IN': update failed: 'RRset exists (value

dependent)' prerequisite not satisfied (NXRRSET)

</para>

</question>

<answer>

<para>

DNS updates allow the update request to test to see if

certain conditions are met prior to proceeding with the

update. The message above is saying that conditions were

not met and the update is not proceeding. See doc/rfc/rfc2136.txt

for more details on prerequisites.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I keep getting log messages like the following. Why?

</para>

<para>

Jun 21 12:00:00.000 client 10.0.0.1#1234: update denied

</para>

</question>

<answer>

<para>

Someone is trying to update your DNS data using the RFC2136

Dynamic Update protocol. Windows 2000 machines have a habit

of sending dynamic update requests to DNS servers without

being specifically configured to do so. If the update

requests are coming from a Windows 2000 machine, see

<ulink

url="http://support.microsoft.com/support/kb/articles/q246/8/04.asp">

&lt;http://support.microsoft.com/support/kb/articles/q246/8/04.asp&gt;</ulink>

for information about how to turn them off.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

When I do a "dig . ns", many of the A records for the root

servers are missing. Why?

</para>

</question>

<answer>

<para>

This is normal and harmless. It is a somewhat confusing

side effect of the way BIND 9 does RFC2181 trust ranking

and of the efforts BIND 9 makes to avoid promoting glue

into answers.

</para>

<para>

When BIND 9 first starts up and primes its cache, it receives

the root server addresses as additional data in an authoritative

response from a root server, and these records are eligible

for inclusion as additional data in responses. Subsequently

it receives a subset of the root server addresses as

additional data in a non-authoritative (referral) response

from a root server. This causes the addresses to now be

considered non-authoritative (glue) data, which is not

eligible for inclusion in responses.

</para>

<para>

The server does have a complete set of root server addresses

cached at all times, it just may not include all of them

as additional data, depending on whether they were last

received as answers or as glue. You can always look up the

addresses with explicit queries like "dig a.root-servers.net A".

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Why don't my zones reload when I do an "rndc reload" or SIGHUP?

</para>

</question>

<answer>

<para>

A zone can be updated either by editing zone files and

reloading the server or by dynamic update, but not both.

If you have enabled dynamic update for a zone using the

"allow-update" option, you are not supposed to edit the

zone file by hand, and the server will not attempt to reload

it.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Why is named listening on UDP port other than 53?

</para>

</question>

<answer>

<para>

Named uses a system selected port to make queries of other

nameservers. This behaviour can be overridden by using

query-source to lock down the port and/or address. See

also notify-source and transfer-source.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I get warning messages like <quote>zone example.com/IN: refresh:

failure trying master 1.2.3.4#53: timed out</quote>.

</para>

</question>

<answer>

<para>

Check that you can make UDP queries from the slave to the master

</para>

<informalexample>

<programlisting>

dig +norec example.com soa @1.2.3.4</programlisting>

</informalexample>

<para>

You could be generating queries faster than the slave can

cope with. Lower the serial query rate.

</para>

<informalexample>

<programlisting>

serial-query-rate 5; // default 20</programlisting>

</informalexample>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I don't get RRSIG's returned when I use "dig +dnssec".

</para>

</question>

<answer>

<para>

You need to ensure DNSSEC is enabled (dnssec-enable yes;).

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Can a NS record refer to a CNAME.

</para>

</question>

<answer>

<para>

No. The rules for glue (copies of the *address* records

in the parent zones) and additional section processing do

not allow it to work.

</para>

<para>

You would have to add both the CNAME and address records

(A/AAAA) as glue to the parent zone and have CNAMEs be

followed when doing additional section processing to make

it work. No nameserver implementation supports either of

these requirements.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

What does <quote>RFC 1918 response from Internet for

0.0.0.10.IN-ADDR.ARPA</quote> mean?

</para>

</question>

<answer>

<para>

If the IN-ADDR.ARPA name covered refers to a internal address

space you are using then you have failed to follow RFC 1918

usage rules and are leaking queries to the Internet. You

should establish your own zones for these addresses to prevent

you querying the Internet's name servers for these addresses.

Please see <ulink url="http://as112.net/">&lt;http://as112.net/&gt;</ulink>

for details of the problems you are causing and the counter

measures that have had to be deployed.

</para>

<para>

If you are not using these private addresses then a client

has queried for them. You can just ignore the messages,

get the offending client to stop sending you these messages

as they are most probably leaking them or setup your own zones

empty zones to serve answers to these queries.

</para>

<informalexample>

<programlisting>

zone "10.IN-ADDR.ARPA" {

type master;

file "empty";

};

zone "16.172.IN-ADDR.ARPA" {

type master;

file "empty";

};

...

zone "31.172.IN-ADDR.ARPA" {

type master;

file "empty";

};

zone "168.192.IN-ADDR.ARPA" {

type master;

file "empty";

};

empty:

@ 10800 IN SOA &lt;name-of-server&gt;. &lt;contact-email&gt;. (

1 3600 1200 604800 10800 )

@ 10800 IN NS &lt;name-of-server&gt;.</programlisting>

</informalexample>

<para>

<note>

Future versions of named are likely to do this automatically.

</note>

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Will named be affected by the 2007 changes to daylight savings

rules in the US.

</para>

</question>

<answer>

<para>

No, so long as the machines internal clock (as reported

by "date -u") remains at UTC. The only visible change

if you fail to upgrade your OS, if you are in a affected

area, will be that log messages will be a hour out during

the period where the old rules do not match the new rules.

</para>

<para>

For most OS's this change just means that you need to

update the conversion rules from UTC to local time.

Normally this involves updating a file in /etc (which

sets the default timezone for the machine) and possibly

a directory which has all the conversion rules for the

world (e.g. /usr/share/zoneinfo). When updating the OS

do not forget to update any chroot areas as well.

See your OS's documentation for more details.

</para>

<para>

The local timezone conversion rules can also be done on

a individual basis by setting the TZ environment variable

appropriately. See your OS's documentation for more

details.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Is there a bugzilla (or other tool) database that mere

mortals can have (read-only) access to for bind?

</para>

</question>

<answer>

<para>

No. The BIND 9 bug database is kept closed for a number

of reasons. These include, but are not limited to, that

the database contains proprietory information from people

reporting bugs. The database has in the past and may in

future contain unfixed bugs which are capable of bringing

down most of the Internet's DNS infrastructure.

</para>

<para>

The release pages for each version contain up to date

lists of bugs that have been fixed post release. That

is as close as we can get to providing a bug database.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Why do queries for NSEC3 records fail to return the NSEC3 record?

</para>

</question>

<answer>

<para>

NSEC3 records are strictly meta data and can only be

returned in the authority section. This is done so that

signing the zone using NSEC3 records does not bring names

into existence that do not exist in the unsigned version

of the zone.

</para>

</answer>

</qandaentry>

</qandadiv> <!-- General Questions -->

<qandadiv><title>Operating-System Specific Questions</title>

<qandadiv><title>HPUX</title>

<qandaentry>

<question>

<para>I get the following error trying to configure BIND:

<programlisting>checking if unistd.h or sys/types.h defines fd_set... no

configure: error: need either working unistd.h or sys/select.h</programlisting>

</para>

</question>

<answer>

<para>

You have attempted to configure BIND with the bundled C compiler.

This compiler does not meet the minimum compiler requirements to

for building BIND. You need to install a ANSI C compiler and / or

teach configure how to find the ANSI C compiler. The later can

be done by adjusting the PATH environment variable and / or

specifying the compiler via CC.

</para>

<informalexample>

<programlisting>/configure CC=&lt;compiler&gt; ...</programlisting>

</informalexample>

</answer>

</qandaentry>

</qandadiv> <!-- HPUX -->

<qandadiv><title>Linux</title>

<qandaentry>

<question>

<para>

Why do I get the following errors:

<programlisting>general: errno2result.c:109: unexpected error:

general: unable to convert errno to isc_result: 14: Bad address

client: UDP client handler shutting down due to fatal receive error: unexpected error</programlisting>

</para>

</question>

<answer>

<para>

This is the result of a Linux kernel bug.

</para>

<para>

See:

<ulink url="http://marc.theaimsgroup.com/?l=linux-netdev&amp;m=113081708031466&amp;w=2">&lt;http://marc.theaimsgroup.com/?l=linux-netdev&amp;m=113081708031466&amp;w=2&gt;</ulink>

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Why does named lock up when it attempts to connect over IPSEC tunnels?

</para>

</question>

<answer>

<para>

This is due to a kernel bug where the fact that a socket is marked

non-blocking is ignored. It is reported that setting

xfrm_larval_drop to 1 helps but this may have negative side effects.

See:

<ulink url="https://bugzilla.redhat.com/show_bug.cgi?id=427629">&lt;https://bugzilla.redhat.com/show_bug.cgi?id=427629&gt;</ulink>

and

<ulink url="http://lkml.org/lkml/2007/12/4/260">&lt;http://lkml.org/lkml/2007/12/4/260&gt;</ulink>.

</para>

<para>

xfrm_larval_drop can be set to 1 by the following procedure:

<programlisting>

echo "1" &gt; proc/sys/net/core/xfrm_larval_drop</programlisting>

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Why do I see 5 (or more) copies of named on Linux?

</para>

</question>

<answer>

<para>

Linux threads each show up as a process under ps. The

approximate number of threads running is n+4, where n is

the number of CPUs. Note that the amount of memory used

is not cumulative; if each process is using 10M of memory,

only a total of 10M is used.

</para>

<para>

Newer versions of Linux's ps command hide the individual threads

and require -L to display them.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Why does BIND 9 log <quote>permission denied</quote> errors accessing

its configuration files or zones on my Linux system even

though it is running as root?

</para>

</question>

<answer>

<para>

On Linux, BIND 9 drops most of its root privileges on

startup. This including the privilege to open files owned

by other users. Therefore, if the server is running as

root, the configuration files and zone files should also

be owned by root.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I get the error message <quote>named: capset failed: Operation

not permitted</quote> when starting named.

</para>

</question>

<answer>

<para>

The capability module, part of "Linux Security Modules/LSM",

has not been loaded into the kernel. See insmod(8), modprobe(8).

</para>

<para>

The relevant modules can be loaded by running:

<programlisting>

modprobe commoncap

modprobe capability</programlisting>

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I'm running BIND on Red Hat Enterprise Linux or Fedora Core -

</para>

<para>

Why can't named update slave zone database files?

</para>

<para>

Why can't named create DDNS journal files or update

the master zones from journals?

</para>

<para>

Why can't named create custom log files?

</para>

</question>

<answer>

<para>

Red Hat Security Enhanced Linux (SELinux) policy security

protections :

</para>

<para>

Red Hat have adopted the National Security Agency's

SELinux security policy (see <ulink

url="http://www.nsa.gov/selinux">&lt;http://www.nsa.gov/selinux&gt;</ulink>)

and recommendations for BIND security , which are more

secure than running named in a chroot and make use of

the bind-chroot environment unnecessary .

</para>

<para>

By default, named is not allowed by the SELinux policy

to write, create or delete any files EXCEPT in these

directories:

<informalexample>

<programlisting>

$ROOTDIR/var/named/slaves

$ROOTDIR/var/named/data

$ROOTDIR/var/tmp

</programlisting>

</informalexample>

where $ROOTDIR may be set in /etc/sysconfig/named if

bind-chroot is installed.

</para>

<para>

The SELinux policy particularly does NOT allow named to modify

the $ROOTDIR/var/named directory, the default location for master

zone database files.

</para>

<para>

SELinux policy overrules file access permissions - so

even if all the files under /var/named have ownership

named:named and mode rw-rw-r--, named will still not be

able to write or create files except in the directories

above, with SELinux in Enforcing mode.

</para>

<para>

So, to allow named to update slave or DDNS zone files,

it is best to locate them in $ROOTDIR/var/named/slaves,

with named.conf zone statements such as:

<informalexample>

<programlisting>

zone "slave.zone." IN {

type slave;

file "slaves/slave.zone.db";

...

};

zone "ddns.zone." IN {

type master;

allow-updates {...};

file "slaves/ddns.zone.db";

};

</programlisting>

</informalexample>

</para>

<para>

To allow named to create its cache dump and statistics

files, for example, you could use named.conf options

statements such as:

<informalexample>

<programlisting>

options {

...

dump-file "/var/named/data/cache_dump.db";

statistics-file "/var/named/data/named_stats.txt";

...

};

</programlisting>

</informalexample>

</para>

<para>

You can also tell SELinux to allow named to update any

zone database files, by setting the SELinux tunable boolean

parameter 'named_write_master_zones=1', using the

system-config-securitylevel GUI, using the 'setsebool'

command, or in /etc/selinux/targeted/booleans.

</para>

<para>

You can disable SELinux protection for named entirely by

setting the 'named_disable_trans=1' SELinux tunable boolean

parameter.

</para>

<para>

The SELinux named policy defines these SELinux contexts for named:

<informalexample>

<programlisting>

named_zone_t : for zone database files - $ROOTDIR/var/named/*

named_conf_t : for named configuration files - $ROOTDIR/etc/{named,rndc}.*

named_cache_t: for files modifiable by named - $ROOTDIR/var/{tmp,named/{slaves,data}}

</programlisting>

</informalexample>

</para>

<para>

If you want to retain use of the SELinux policy for named,

and put named files in different locations, you can do

so by changing the context of the custom file locations

.

</para>

<para>

To create a custom configuration file location, e.g.

'/root/named.conf', to use with the 'named -c' option,

do:

<informalexample>

<programlisting>

# chcon system_u:object_r:named_conf_t /root/named.conf

</programlisting>

</informalexample>

</para>

<para>

To create a custom modifiable named data location, e.g.

'/var/log/named' for a log file, do:

<informalexample>

<programlisting>

# chcon system_u:object_r:named_cache_t /var/log/named

</programlisting>

</informalexample>

</para>

<para>

To create a custom zone file location, e.g. /root/zones/, do:

<informalexample>

<programlisting>

# chcon system_u:object_r:named_zone_t /root/zones/{.,*}

</programlisting>

</informalexample>

</para>

<para>

See these man-pages for more information : selinux(8),

named_selinux(8), chcon(1), setsebool(8)

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I'm running BIND on Ubuntu -

</para>

<para>

Why can't named update slave zone database files?

</para>

<para>

Why can't named create DDNS journal files or update

the master zones from journals?

</para>

<para>

Why can't named create custom log files?

</para>

</question>

<answer>

<para>

Ubuntu uses AppArmor <ulink url="http://en.wikipedia.org/wiki/AppArmor">

&lt;http://en.wikipedia.org/wiki/AppArmor&gt;</ulink> in

addition to normal file system permissions to protect the system.

</para>

<para>

Adjust the paths to use those specified in /etc/apparmor.d/usr.sbin.named

or adjust /etc/apparmor.d/usr.sbin.named to allow named to write at the

location specified in named.conf.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

Listening on individual IPv6 interfaces does not work.

</para>

</question>

<answer>

<para>

This is usually due to "/proc/net/if_inet6" not being available

in the chroot file system. Mount another instance of "proc"

in the chroot file system.

</para>

<para>

This can be be made permanent by adding a second instance to

/etc/fstab.

<informalexample>

<programlisting>

proc /proc proc defaults 0 0

proc /var/named/proc proc defaults 0 0</programlisting>

</informalexample>

</para>

</answer>

</qandaentry>

</qandadiv> <!-- Linux -->

<qandadiv><title>Windows</title>

<qandaentry>

<question>

<para>

Zone transfers from my BIND 9 master to my Windows 2000

slave fail. Why?

</para>

</question>

<answer>

<para>

This may be caused by a bug in the Windows 2000 DNS server

where DNS messages larger than 16K are not handled properly.

This can be worked around by setting the option "transfer-format

one-answer;". Also check whether your zone contains domain

names with embedded spaces or other special characters,

like "John\032Doe\213s\032Computer", since such names have

been known to cause Windows 2000 slaves to incorrectly

reject the zone.

</para>

</answer>

</qandaentry>

<qandaentry>

<question>

<para>

I get <quote>Error 1067</quote> when starting named under Windows.

</para>

</question>

<answer>

<para>

This is the service manager saying that named exited. You

need to examine the Application log in the EventViewer to

find out why.

</para>

<para>

Common causes are that you failed to create "named.conf"

(usually "C:\windows\dns\etc\named.conf") or failed to

specify the directory in named.conf.

</para>

<informalexample>

<programlisting>

options {

Directory "C:\windows\dns\etc";

};</programlisting>

</informalexample>

</answer>

</qandaentry>

</qandadiv> <!-- Windows -->

<qandadiv><title>FreeBSD</title>

<qandaentry>

<question>

<para>

I have FreeBSD 4.x and "rndc-confgen -a" just sits there.

</para>

</question>

<answer>

<para>

/dev/random is not configured. Use rndcontrol(8) to tell

the kernel to use certain interrupts as a source of random

events. You can make this permanent by setting rand_irqs

in /etc/rc.conf.

</para>

<informalexample>

<programlisting>

rand_irqs="3 14 15"</programlisting>

</informalexample>

<para>

See also

<ulink url="http://people.freebsd.org/~dougb/randomness.html">

&lt;http://people.freebsd.org/~dougb/randomness.html&gt;</ulink>.

</para>

</answer>

</qandaentry>

</qandadiv> <!-- FreeBSD -->

<qandadiv><title>Solaris</title>

<qandaentry>

<question>

<para>

How do I integrate BIND 9 and Solaris SMF

</para>

</question>

<answer>

<para>

Sun has a blog entry describing how to do this.

</para>

<para>

<ulink

url="http://blogs.sun.com/roller/page/anay/Weblog?catname=%2FSolaris">

&lt;http://blogs.sun.com/roller/page/anay/Weblog?catname=%2FSolaris&gt;

</ulink>

</para>

</answer>

</qandaentry>

</qandadiv>

<qandadiv><title>Apple Mac OS X</title>

<qandaentry>

<question>

<para>

How do I run BIND 9 on Apple Mac OS X?

</para>

</question>

<answer>

<para>

If you run Tiger(Mac OS 10.4) or later then this is all you need to do:

</para>

<informalexample>

<programlisting>

% sudo rndc-confgen > /etc/rndc.conf</programlisting>

</informalexample>

<para>

Copy the key statement from /etc/rndc.conf into /etc/rndc.key, e.g.:

</para>

<informalexample>

<programlisting>

key "rndc-key" {

algorithm hmac-sha256;

secret "uvceheVuqf17ZwIcTydddw==";

};</programlisting>

</informalexample>

<para>

Then start the relevant service:

</para>

<informalexample>

<programlisting>

% sudo service org.isc.named start</programlisting>

</informalexample>

<para>

This is persistent upon a reboot, so you will have to do it only once.

</para>

</answer>

<answer>

<para>

Alternatively you can just generate /etc/rndc.key by running:

</para>

<informalexample>

<programlisting>

% sudo rndc-confgen -a</programlisting>

</informalexample>

<para>

Then start the relevant service:

</para>

<informalexample>

<programlisting>

% sudo service org.isc.named start</programlisting>

</informalexample>

<para>

Named will look for /etc/rndc.key when it starts if it

doesn't have a controls section or the existing controls are

missing keys sub-clauses. This is persistent upon a

reboot, so you will have to do it only once.

</para>

</answer>

</qandaentry>

</qandadiv>

</qandadiv> <!-- Operating-System Specific Questions -->

</qandaset>

</article>