You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: local_link_resolver.rb
    path of file: ./repos/middleman/middleman-core/lib/middleman-core/dns_resolver
    
    the code of the file until where you have to start completion: require 'middleman-core/dns_resolver/basic_network_resolver'

module Middleman
  class DnsResolver
    # Use network name server to resolve ips a
    
      def nameserver_config
        return unless ENV.key?('MM_MDNSRC') && ENV['MM_MDNSRC']

        address, port = ENV['MM_MDNSRC'].split(/:/)

        {
          nameserver_port: [[address, port.to_i]]
        }
      rescue StandardError
        {}
      end