While implementing QOS the default class is implemented with best effort traffic. Best effort class uses DSCP marking 46. We have one more class which is below to default class, the class is recognized by scavenger class. It provides the less than best effort service. The class is used to distinguish lobotomize traffic. MArking use for class is CS1 or DSCP 8. The major advantage of class comes out when network is flooded with DOS attack & all type of traffic is being added to the class with 1% of bandwdith or what ever you want.