Internet-based DOS attacks can more easily be distributed, meaning there can be multiple machines (often hundreds or thousands, some of them "enslaved" through viruses) sending communications to a particular website -- or technically, to the server on which the site is stored -- that simply overload the server's capacity and could cause it to crash or simply to provide communications that are too slow to be intelligible (Roebuck, 2005; Cross, 2008; Raghavan & Dawson, 2011). The possibilities and the distance involved make Internet DOS attacks more complex, but with the proper know-how they can be easier to achieve consistently for attackers (Roebuck, 2005). Preventing DOS attacks can be all but impossible, especially in an Internet setting, but taking steps to ensure that a website/server can easily recover from a DOS attack and restore reliable service to users can help reduce the likelihood of that being targeted -- if the attack cannot have much of an effect, it isn't worth much effort (Vaughan-Nichols, 2010). In order to accomplish this, a consistent recommendation among it security experts is to have the latest and greatest technologies and services available, from hosting services to network gateways and firewalls and whatever other pieces of hardware and software architecture are involved in keeping a website live or a network running (Vaughan-Nichols, 2010; Schwartz, 2012). This, combined with planning that includes back-up means of serving consumer/business needs and an understanding of the lack of control when it comes to confronting...

Though they are not directly destructive, they can create enormous costs and losses for businesses and all manner of other organizations, and it is necessary to be prepared for the possibility of such an attack on any website or computer network. The research presented above yields recommendations of regularly updating all elements of a website or networks architecture and having a backup plan ready, but these are the only ways to effectively combat DOS attacks. For now, the attackers have the advantage.
References

Cross, M. (2008). Scene of the Cybercrime. Burlington, MA: Elsevier.

Roebuck, T. (2005). DoS and DDoS Attacks. Computer Crime Research Center. Accessed 8 September 2012. http://www.crime-research.org/articles/network-security-dos-ddos-attacks/

Raghavan, S. & Dawson, E. (2011). An Investigation into the Detection and Mitigation of Denial of Service (DoS) Attacks. New York: Springer.

Schwartz, M. (2012). 10 Strategies to Fight Anonymous DDoS Attacks. InformationWeek. Accessed 8 September 2012. http://www.informationweek.com/security/vulnerabilities/10-strategies-to-fight-anonymous-ddos-at/232600411?pgno=1

Vaughan-Nichols, S. (2010). How to try to stop DDoS Attacks. ZDNet. Accessed 8 September 2012. http://www.zdnet.com/blog/networking/how-to-try-to-stop-ddos-attacks/440