DNS views are a fairly
recent (12.4ish) addition to IOS to provide the capability for some
advanced DNS name server functionality. They allow you to utilize
the router as a DNS server and segregate DNS names + forwarding.
This comes in handy when you want a split DNS environment - i.e.,
different name spaces and forwarding for different segments of the
network. Obviously, you’re not likely to see the enterprise using
the router as a DNS server – but it’s quite effective in the
small network builder space (home network for instance).
The starting point in
this configuration is creation of the view itself.
ip
dns view internal
domain
name abcxyz.com
domain
name-server 8.8.8.8
domain
name-server 8.8.4.4
The command above
creates the DNS view named "internal", sets the domain name
to "abcxyz.com" and sets up DNS forwarding to a pair of
Google's DNS servers.
Now, I can create my
own DNS namespace within that view.
ip
host view internal server1 192.168.1.111
ip
host view internal server2 192.168.1.112
ip
host view internal server3 192.168.1.112
ip
host view internal server4 192.168.1.114
ip
host view internal server5 192.168.1.115
Next step is to assign
the view to a ‘view list’. A view list is an ordered list of
view where you can put additional restrictions. A view list is also
what you assign to a network segment (interface). For this exercise,
we’re just adding 1 view to a list named ‘internallist’ (note
the highly creative naming conventions I’m using).
ip
dns view-list internallist
view
internal 1
Now, I assign the view
list to a subinterface/VLAN.
interface
FastEthernet0/1.1
description
data vlan
encapsulation
dot1Q 1 native
ip
address 192.168.1.1 255.255.255.0
ip
dns view-group internallist
ip
nat inside
Done. Now, this VLAN
has visibility to the “internal” DNS namespace above and utilizes
DNS forwarding to Google’s DNS servers.
Copyright ©1993-2024 Joey E Whelan, All rights reserved.
