The zones.rfc1918 file is a preconfigured zone file in BIND9 that contains definitions for reverse mapping of private IP addresses defined in RFC 1918 (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16). Its primary purposes are:

• Preventing accidental exposure of internal DNS queries to the public internet
• Blocking reverse DNS lookups for private addresses from reaching root servers
• Supporting split-DNS configurations in view-based setups

When using views with RFC1918 subnets, common errors occur because:

// Typical error example
named[1234]: zones.rfc1918:10: zone '10.in-addr.arpa/IN': already exists

This happens when your view configuration overlaps with the default zones.rfc1918 definitions.

Here's how to properly integrate RFC1918 addresses with views:

// named.conf options snippet
include "/etc/bind/zones.rfc1918";

view "internal" {
    match-clients { 192.168.1.0/24; 10.0.0.0/8; };
    recursion yes;
    
    // Override specific RFC1918 zones for this view
    zone "10.in-addr.arpa" {
        type master;
        file "/etc/bind/internal/db.10";
    };
};

view "external" {
    match-clients { any; };
    recursion no;
};

When working with RFC1918 addresses in BIND9:

1. Keep the zones.rfc1918 include but override specific zones in views
2. Ensure each view has its own copy of reverse zone files
3. Use explicit zone definitions rather than relying on defaults

For Ubuntu 10.04 LTS specifically:

# Check for syntax errors
named-checkconf /etc/bind/named.conf

# Verify zone files
named-checkzone example.com /etc/bind/zones/db.example.com

# Reload configuration
/etc/init.d/bind9 reload

The zones.rfc1918 file is a default configuration component in BIND9 that defines authoritative DNS zones for reverse mapping of private IP addresses (RFC1918 ranges). These include:

• 10.0.0.0/8
• 172.16.0.0/12
• 192.168.0.0/16

When implementing DNS views for different subnets (common in enterprise environments), the zones.rfc1918 file becomes particularly relevant. BIND9 uses this file to:

1. Prevent accidental exposure of internal DNS data to external clients
2. Handle reverse DNS lookups for private addresses consistently
3. Maintain proper zone authority boundaries

Here's how to properly configure views while accounting for RFC1918 zones:

// named.conf.local excerpt
view "internal" {
    match-clients { 192.168.1.0/24; 10.0.0.0/8; };
    include "/etc/bind/zones.rfc1918";
    
    zone "example.local" {
        type master;
        file "/etc/bind/db.example.local";
    };
};

view "external" {
    match-clients { any; };
    recursion no;
    
    zone "example.com" {
        type master;
        file "/etc/bind/db.example.com";
    };
};

Problem: Errors about missing RFC1918 zone authority
Solution: Either:

• Keep the default zones.rfc1918 inclusion, or
• Explicitly define the zones in your view configuration

For complete control, you might create custom versions:

zone "10.in-addr.arpa" { type master; file "db.empty"; };
zone "16.172.in-addr.arpa" { type master; file "db.empty"; };
zone "168.192.in-addr.arpa" { type master; file "db.empty"; };

Including zones.rfc1918 has minimal performance impact as:

• The zones are typically empty or contain minimal records
• They only affect reverse DNS queries for private addresses
• Modern BIND9 implementations handle these efficiently

The file serves as a safeguard rather than an operational burden, helping maintain DNS hygiene in environments using private addressing.