To be clear, I'd rewrite to:
```
slave_nodes.each do |n|
  node = NodeObject.find_node_by_name n
  node[:dns][:master] = false
  slaves_ip << node[:crowbar][:network][:admin][:address]
  node.save
end

master[:dns][:master] = true

tnodes.each do |n|
  node = NodeObject.find_node_by_name n
  node[:dns][:master_ip] = master[:crowbar][:network][:admin][:address]
  node[:dns][:slaves_ip] = slaves_ip
  node[:dns][:slaves_name] = slave_nodes
  node.save
end
```

(ideally, we would only use ```node.save``` if there's really a change)