### BIND 9 View Statement Example

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

Demonstrates a split DNS setup using 'view' statements to provide different responses to internal and external clients for the same zone.

```bind
view "internal" {
        // This should match our internal networks.
        match-clients { 10.0.0.0/8; };

        // Provide recursive service to internal
        // clients only.
        recursion yes;

        // Provide a complete view of the example.com
        // zone including addresses of internal hosts.
        zone "example.com" {
          type primary;
          file "example-internal.db";
        };
  };

  view "external" {
        // Match all clients not matched by the
        // previous view.
        match-clients { any; };

        // Refuse recursive service to external clients.
        recursion no;

        // Provide a restricted view of the example.com
        // zone containing only publicly accessible hosts.
        zone "example.com" {
         type primary;
         file "example-external.db";
        };
  };
```

--------------------------------

### C++-Style Comment Example

Source: https://bind9.readthedocs.io/en/stable/reference.html

Illustrates C++-style comments, which start with // and extend to the end of the physical line. Each line requires its own //.

```bindconfig
// This is the start of a comment.  The next line
// is a new comment, even though it is logically
// part of the previous comment.


```

--------------------------------

### Example nsupdate with Dynamic Update Policy

Source: https://bind9.readthedocs.io/en/stable/reference.html

This example demonstrates how to use the `nsupdate` utility to perform a dynamic DNS update, specifically deleting an existing PTR record and adding a new one, in conjunction with a configured update policy. Ensure the `local` option is set to the correct IP address of the nameserver.

```shell
nsupdate -v <<EOF
local 192.0.2.1
del 1.2.0.192.IN-ADDR.ARPA PTR
add 1.2.0.192.IN-ADDR.ARPA 0 PTR EXAMPLE.COM
send
EOF

```

--------------------------------

### Example DNSSEC Policy Keys Configuration

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

This example demonstrates how to configure keys for DNSSEC signing within a `dnssec-policy` statement. It specifies key-signing keys (KSK) and zone-signing keys (ZSK) with their algorithms, lifetimes, and key sizes.

```bindconf
keys {
    ksk key-directory lifetime unlimited algorithm rsasha256 2048;
    zsk lifetime 30d algorithm 8 tag-range 0 32767;
}
```

--------------------------------

### C++-style Comment Example

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

Illustrates C++-style comments, which start with // and continue to the end of the line. Each line of a multi-line comment requires its own //.

```none
// This is the start of a comment.  The next line
// is a new comment, even though it is logically
// part of the previous comment.
```

--------------------------------

### BIND 9 Split DNS Configuration with Views

Source: https://bind9.readthedocs.io/en/stable/reference.html

This example demonstrates a typical split DNS setup using 'view' statements in BIND 9. It defines two views, 'internal' and 'external', to provide different DNS responses to clients based on their IP addresses. The 'internal' view allows recursive service and includes internal host addresses, while the 'external' view restricts recursive service and provides only publicly accessible host information.

```bind
view "internal" {
      // This should match our internal networks.
      match-clients { 10.0.0.0/8; };

      // Provide recursive service to internal
      // clients only.
      recursion yes;

      // Provide a complete view of the example.com
      // zone including addresses of internal hosts.
      zone "example.com" {
        type primary;
        file "example-internal.db";
      };
};

view "external" {
      // Match all clients not matched by the
      // previous view.
      match-clients { any; };

      // Refuse recursive service to external clients.
      recursion no;

      // Provide a restricted view of the example.com
      // zone containing only publicly accessible hosts.
      zone "example.com" {
       type primary;
       file "example-external.db";
      };
};

```

--------------------------------

### Inverse Mapping PTR Record Example

Source: https://bind9.readthedocs.io/en/stable/chapter3.html

Illustrates how to set up a PTR record for reverse DNS lookups in the in-addr.arpa domain. The example shows the record relative to the $ORIGIN.

```dns
$ORIGIN | 2.1.10.in-addr.arpa
--|--
3 | IN PTR foo.example.com.
```

--------------------------------

### DNSSEC Key File Example

Source: https://bind9.readthedocs.io/en/stable/dnssec-guide.html

Example of a DNSSEC key-signing key (KSK) file. The first line indicates the key type, and the DNSKEY record specifies the key details. ZSK keys are indicated by 256, and KSK keys by 257.

```text
; This is a key-signing key, keyid 472, for example.com.
; Created: 20200616104254 (Tue Jun 16 11:42:54 2020)
; Publish: 20200616104254 (Tue Jun 16 11:42:54 2020)
; Activate: 20200616104254 (Tue Jun 16 11:42:54 2020)
example.com. IN DNSKEY 257 3 13 AwEAAbCR6U...l8xPjokVU=
```

--------------------------------

### RPZ Zone File Example

Source: https://bind9.readthedocs.io/en/stable/reference.html

An example of a BIND 9 Response Policy Zone (RPZ) file. It demonstrates various policy record types like NXDOMAIN, NODATA, redirection, passthru, IP-based rewriting, and client-specific policies.

```dns
$TTL 1H
@                       SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h)
            NS  LOCALHOST.

; QNAME policy records.  There are no periods (.) after the owner names.
nxdomain.domain.com     CNAME   .               ; NXDOMAIN policy
*.nxdomain.domain.com   CNAME   .               ; NXDOMAIN policy
nodata.domain.com       CNAME   *.              ; NODATA policy
*.nodata.domain.com     CNAME   *.              ; NODATA policy
bad.domain.com          A       10.0.0.1        ; redirect to a walled garden
            AAAA    2001:2::1
bzone.domain.com        CNAME   garden.example.com.

; do not rewrite (PASSTHRU) OK.DOMAIN.COM
ok.domain.com           CNAME   rpz-passthru.

; redirect x.bzone.domain.com to x.bzone.domain.com.garden.example.com
*.bzone.domain.com      CNAME   *.garden.example.com.

; IP policy records that rewrite all responses containing A records in 127/8
;       except 127.0.0.1
8.0.0.0.127.rpz-ip      CNAME   .
32.1.0.0.127.rpz-ip     CNAME   rpz-passthru.

; NSDNAME and NSIP policy records
ns.domain.com.rpz-nsdname   CNAME   .
48.zz.2.2001.rpz-nsip       CNAME   .

; auto-reject and auto-accept some DNS clients
112.zz.2001.rpz-client-ip    CNAME   rpz-drop.
8.0.0.0.127.rpz-client-ip    CNAME   rpz-drop.

; force some DNS clients and responses in the example.com zone to TCP
16.0.0.1.10.rpz-client-ip   CNAME   rpz-tcp-only.
example.com                 CNAME   rpz-tcp-only.
*.example.com               CNAME   rpz-tcp-only.

```

--------------------------------

### RPZ Zone File Examples

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

Examples of various record types within an RPZ zone file, including QNAME, IP, NSDNAME, NSIP, client-ip, and redirection policies.

```BIND Zone File
$TTL 1H
@                       SOA LOCALHOST. named-mgr.example.com (1 1h 15m 30d 2h)
            NS  LOCALHOST.

; QNAME policy records.  There are no periods (.) after the owner names.
nxdomain.domain.com     CNAME   .               ; NXDOMAIN policy
*.nxdomain.domain.com   CNAME   .               ; NXDOMAIN policy
nodata.domain.com       CNAME   *.              ; NODATA policy
*.nodata.domain.com     CNAME   *.              ; NODATA policy
bad.domain.com          A       10.0.0.1        ; redirect to a walled garden
            AAAA    2001:2::1
bzone.domain.com        CNAME   garden.example.com.

; do not rewrite (PASSTHRU) OK.DOMAIN.COM
ok.domain.com           CNAME   rpz-passthru.

; redirect x.bzone.domain.com to x.bzone.domain.com.garden.example.com
*.bzone.domain.com      CNAME   *.garden.example.com.

; IP policy records that rewrite all responses containing A records in 127/8
;       except 127.0.0.1
8.0.0.0.127.rpz-ip      CNAME   .
32.1.0.0.127.rpz-ip     CNAME   rpz-passthru.

; NSDNAME and NSIP policy records
ns.domain.com.rpz-nsdname   CNAME   .
48.zz.2.2001.rpz-nsip       CNAME   .

; auto-reject and auto-accept some DNS clients
112.zz.2001.rpz-client-ip    CNAME   rpz-drop.
8.0.0.0.127.rpz-client-ip    CNAME   rpz-drop.

; force some DNS clients and responses in the example.com zone to TCP
16.0.0.1.10.rpz-client-ip   CNAME   rpz-tcp-only.
example.com                 CNAME   rpz-tcp-only.
*.example.com               CNAME   rpz-tcp-only.
```

--------------------------------

### Example of Deny Answer Configuration

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

Illustrates how to configure deny-answer-addresses and deny-answer-aliases to prevent DNS rebinding attacks, including exceptions.

```bindconf
deny-answer-addresses { 192.0.2.0/24; } except-from { "example.net"; };
deny-answer-aliases { "example.net"; };
```

--------------------------------

### Basic RPZ Zone Configuration

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

Example of a basic response-policy statement enabling a zone for RPZ.

```BIND Configuration
response-policy {
    zone "badlist";
};
```

--------------------------------

### BIND Configuration Layout Styles

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

Provides examples of different layout styles for BIND configuration files, including dense single-line, single-statement-per-line, and a mixed style.

```none
	// dense single-line style
	zone "example.com" in{type secondary; file "secondary.example.com"; primaries {10.0.0.1;};};
	//  single-statement-per-line style
	zone "example.com" in{
		type secondary;
		file "secondary.example.com";
		primaries {10.0.0.1;};
	};
	// spot the difference
	zone "example.com" in{
		type secondary;
	file "sec.secondary.com";
	primaries {10.0.0.1; }; }
```

--------------------------------

### Configure BIND 9 Build Options

Source: https://bind9.readthedocs.io/en/stable/chapter10.html

View available configuration options for BIND 9 by running the configure script with the --help flag.

```bash
$ ./configure --help

```

--------------------------------

### DLZ Configuration with Search Enabled

Source: https://bind9.readthedocs.io/en/stable/chapter6.html

Configures a Dynamically Loadable Zone (DLZ) named 'example' using a shared object driver. The 'search yes' option indicates that this DLZ module should be queried for answers to incoming queries. 'yes' is the default.

```dns
dlz example {
database "dlopen driver.so args";
search yes;
};


```

--------------------------------

### Example A Record for Verification

Source: https://bind9.readthedocs.io/en/stable/dnssec-guide.html

This is the plain text A record for ftp.isc.org used in the DNSSEC verification example.

```dns
ftp.isc.org.     4 IN A  149.20.1.49

```

--------------------------------

### Build and Install SoftHSMv2 with OpenSSL Backend (Bash)

Source: https://bind9.readthedocs.io/en/stable/chapter5.html

Configure, build, and install SoftHSMv2 using OpenSSL as the crypto backend. This prepares a virtual HSM for PKCS#11 integration. Ensure the prefix is set correctly for installation.

```bash
$  cd SoftHSMv2
$  configure --with-crypto-backend=openssl --prefix=/opt/pkcs11/usr
$  make
$  make install
$  /opt/pkcs11/usr/bin/softhsm-util --init-token 0 --slot 0 --label softhsmv2

```

--------------------------------

### Example DS RR output

Source: https://bind9.readthedocs.io/en/stable/manpages.html

This is an example of the output generated by dnssec-dsfromkey, showing the DS record format.

```text
example.com. IN DS 26160 5 2 3A1EADA7A74B8D0BA86726B0C227AA85AB8BBD2B2004F41A868A54F0C5EA0B94
```

--------------------------------

### Configure Sample DynDB Module

Source: https://bind9.readthedocs.io/en/stable/chapter6.html

This configuration loads a sample DynDB module, specifying the shared object file and the zones it will manage.

```bindconfig
dyndb sample "sample.so" { example.nil. arpa. };

```

--------------------------------

### Configure a Hint Zone

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

Specify the initial set of root name servers using a hint zone. If no hint zone is specified for class IN, BIND uses a compiled-in default.

```BIND Configuration
zone "." {
    type hint;
    file "named.ca";
};
```

--------------------------------

### Wildcard MX Record Example

Source: https://bind9.readthedocs.io/en/stable/chapter6.html

This is an example of a wildcard MX record used to direct mail for any subdomain to a specific external mail server.

```dns
*   IN MX 10 external1.example.com.

```

--------------------------------

### C-Style Comment Example (Invalid Nesting)

Source: https://bind9.readthedocs.io/en/stable/reference.html

Demonstrates C-style comments in BIND configuration. Note that C-style comments cannot be nested and the example shows an invalid nesting attempt.

```bindconfig
/* This is the start of a comment.
   This is still part of the comment.
/* This is an incorrect attempt at nesting a comment. */
   This is no longer in any comment. */

```

--------------------------------

### Configure NSEC3 Parameters

Source: https://bind9.readthedocs.io/en/stable/_sources/reference.rst.txt

Use NSEC3 instead of NSEC for authenticated denial of existence. This example shows default parameters for iterations, opt-out, and salt length.

```bindconf
nsec3param iterations 0 optout no salt-length 0;
```

--------------------------------

### BIND Configuration Layout Styles

Source: https://bind9.readthedocs.io/en/stable/reference.html

Provides examples of different layout styles for BIND configuration files to help minimize errors. Includes dense single-line, single-statement-per-line, and a mixed style.

```bindconfig
// dense single-line style
zone "example.com" in{type secondary; file "secondary.example.com"; primaries {10.0.0.1;};};

```

```bindconfig
//  single-statement-per-line style
zone "example.com" in{
        type secondary;
        file "secondary.example.com";
        primaries {10.0.0.1;};
};

```

```bindconfig
// spot the difference
zone "example.com" in{
        type secondary;
file "sec.secondary.com";
primaries {10.0.0.1;}; };

```

--------------------------------

### Build BIND 9 from Source

Source: https://bind9.readthedocs.io/en/stable/chapter10.html

Standard commands to build BIND 9 on a Unix or Linux system. Run autoreconf if building from a git repository.

```bash
$ autoreconf -fi ### (only if building from the git repository)
$ ./configure
$ make

```

--------------------------------

### Remove Deterministic Nameserver Selection

Source: https://bind9.readthedocs.io/en/stable/changelog.html

Uses a random starting point for selecting nameserver addresses to avoid resolution failures due to always picking from the start of the rrset.

```text
When selecting nameserver addresses to be looked up we where always selecting them in dnssec name order from the start of the nameserver rrset. This could lead to resolution failure despite there being address that could be resolved for the other names. Use a random starting point when selecting which names to lookup.
```

--------------------------------

### Bind9 $ORIGIN Directive Example

Source: https://bind9.readthedocs.io/en/stable/chapter3.html

Demonstrates the use of the $ORIGIN directive to set the default domain name for unqualified records. This example shows how 'WWW CNAME MAIN-SERVER' is expanded.

```dns
$ORIGIN example.com.
WWW     CNAME   MAIN-SERVER
```

```dns
WWW.EXAMPLE.COM. CNAME MAIN-SERVER.EXAMPLE.COM.
```