# File lib/Dnsruby/zone_reader.rb, line 423
    def replace_soa_ttl_fields(line)
      # Replace any fields which evaluate to 0
      split = line.split
      4.times {|i|
        x = i + 7
        split[x].strip!
        split[x] = get_ttl(split[x]).to_s
      }
      return split.join(" ") + "\n"
    end