Is there any method to prevent/trace ddos attack?

I have a debian linux server which run a few online game services. I have some competitors in this area and i think one of them is behind the ddos attacks.

I have full access to the router, so I set a few connection rules in Winbox which can detect and drop the ddoser ip addresses but i think it not the best way to prevent an attack.

These are some source ip address (all from 53 port)

• 38.111.134.26 41.78.27.213 66.232.92.39 66.232.92.43 66.243.192.11 67.43.55.110 67.43.55.111 67.50.161.103 67.59.80.28 67.118.192.2 69.27.136.10 69.27.136.12 69.27.211.200 69.31.186.27 74.114.48.151 116.199.220.101 203.87.92.4 203.161.128.249 203.161.159.10 206.51.97.91 206.158.2.91 209.240.96.6

Is there any method to prevent or trace ddos attack?