Content delivery services provider Akamai Technologies plans to buy Prolexic Technologies, a distributed denial-of-service (DDoS) mitigation specialist, for $370 million in cash.

Akamai, in Cambridge, Massachusetts, runs one of the world's largest content delivery networks with 137,000 servers in 87 countries. Its clients span a variety of industries and include a third of the companies on the Fortune Global 500 list.

Akamai already offers security services that protect Web sites and Web applications against a variety of threats, including DDoS attacks. However, Prolexic, located in Hollywood, Florida, specializes in defending enterprise applications against application-layer and network-layer attacks.

By acquiring Prolexic, Akamai wants to expand its services and provide customers with the technology needed to protect Web and IP infrastructure.

The transaction is pending regulatory approvals and is expected to close in the first half of 2014.

According to Scott Hammack, CEO of Prolexic, combining the expertise of both companies will allow customers to use a single provider for the Internet performance and security needs of their applications, which will simplify the resolution of network availability issues and clarify accountability.

Prolexic operates a network of so-called scrubbing centers spread around the world that have a combined bandwidth of more than 1.5 Tbps. When a DDoS attack occurs, the targeted customer routes in-bound traffic to the nearest Prolexic center, which has enough bandwidth capacity to analyze it and apply DDoS filtering techniques in order to identify and drop the malicious packets. The clean, scrubbed traffic is then routed back to the customer.

The size and number of DDoS attacks has increased significantly in recent years and the methods used by attackers have become more sophisticated, according to past reports from Prolexic and other DDoS mitigation vendors.