Is this a DDOS attack?

I lost my internet connection for about 15 minutes and i checked my netgear router log and found theese 3:

[DoS Attack: ACK Scan] from source: 114.77.184.189, port 44822, Tuesday, March 24,2015 19:08:15 [DoS Attack: ACK Scan] from source: 91.135.35.51, port 80, Tuesday, March 24,2015 18:53:17 [DoS Attack: ACK Scan] from source: 193.66.251.213, port 80, Tuesday, March 24,2015 18:51:31

My connection is slow and i loose internet completly from time to time, but i've never checked the logs before. Is this an attack?