Sometimes abbreviated as DoS attacks, sometimes referred to as DDoS 

"DoS attacks are relatively  simple to perform but can have  devastating effects. They  disable Web sites and routers  by flooding them with false  information requests. In order to discover the source of the requests, technicians must sort through thousands of lines of computer code. DoS attacks can last hours or  days, depending on how quickly they are detected."
Tim McDonald

"Since 2012, the number of infrastructure attacks on the domain name system (DNS) has increased by over 200%. Yet despite this rise, many businesses still aren’t doing enough to secure a critical component of their IT infrastructure."

Ben Rossi on 17 February 2015

BASICs

Essentially DNS attacks done from hijacked computers which means it is difficult for the attacked entity to determine the true source of the threat.

When these were first launched, many were done through networked computers at universities and colleges making it difficult to trace the individual responsible.
.
in Greenstein's book Electronic Commerce Security, 2nd ed.
Chpt 7 Risks of Insecure Systems,  p. 225

"The attacker requests the establishment of a new connection with the target via a SYN (synchronization) packet. The receiving site, the target in this case, responds with a SYN/ACK (synchronization/acknowledgement) packet. At this point, the connection is half-open. The target computer's memory buffer maintains the information while it waits for the initiating server to respond with an ACK (acknowledgment) packet and complete the connection. The final ACK packet is never sent and the connection remains half-open. If enough of these SYN packets are sent to the targeted site, the memory buffers become full and legitimate users' SYN packets are unable to get through"
.
in Greenstein's book Electronic Commerce Security, 2nd ed.
Chpt 7 Risks of Insecure Systems, 

First became known in the general public in February 2000 when several large sites were crippled, some of them for several hours.
 

BusinessWeek article interviewing Bruce Schneier about "distributed denial-of-service attacks"  www.businessweek.com/2000/00_10/b3671089.htm.

Q: BusinessWeek - Is there any defense against distributed denial-of-service attacks?
A: Schneier, - "We don't really know how to defend against this kind of thing. All the defenses
I've heard of are of the civic hygiene variety--in other words, making sure all computers on the Net are secure. But that isn't possible, technically. Even if you put firewalls around 99.99% of computers--which is very unlikely--malicious programs would sniff out the remainder that weren't secured".

"A recent report from the CERT Internet security center at Carnegie Mellon University  indicated that denial of service
 attacks are getting easier to  create and are having greater
 impact. "
 

The CERT paper on DNS was produced by Kevin Houle and George Weaver

E-commerce Times reported on Denial of Service Attacks in February 2000 and a year later ran some stories on how this new threat was significant at the time.

McDonald's short piece centers on some of the new technologies that are helping companies at risk, detect a DOS attack in the beginning and head it off.

"Adding to a growing list of Internet security firms jockeying to establish a viable defense against costly Denial-of-Service (DoS) attacks, an Internet security firm claimed Monday that it has developed a new way to detect, trace and block DoS attacks before they reach their intended online targets.  The company, Arbor Networks of Waltham, Massachusetts,...claims its technology, which uses 'fingerprints' to monitor and
 trace sharp spikes in Web traffic, allows operators to block a DoS attack from
 the company's operations center."
 

From Arbor's web site  www.arbornetworks.com "The Arbor solution uses network topology data and fine-grained traffic statistics to detect, trace, and filter network threats, such as Denial of Service attacks...By regularly sampling network traffic statistics, Arbor’s technology establishes a dynamic profile of typical traffic patterns in different zones of the network. Sampling against this dynamic baseline allows the solution  to flag anomalies."

Denial
of
Service
Attacks
Reported
in the
Online
Media

Yahoo carried an Associated Press story in Oct 23rd, 2002. Powerful Attack Cripples Servers

"But most Internet users didn't notice because the attack only lasted an hour. Its origin was not known,   and the FBI and White House were investigating. One official described Monday's attack as the most      sophisticated and large-scale assault against these  crucial computers in the history of the Internet. Seven of the 13 servers failed to respond to legitimate  network traffic and two others failed intermittently during the attack, officials confirmed.   The FBI's National Infrastructure Protection Center was "aware of the denial of service attack and is addressing this matter," spokesman Steven Berry said. Service was restored after experts enacted defensive measures and the attack  suddenly stopped. The 13 computers are spread geographically across the globe as precaution  against physical disasters and operated by U.S. government agencies,  universities, corporations and private organizations."
 

Getting
The
Word
Out
 

Getting
The
Word
Out
 

A VeriSign Global Registry Services Herndon VA, US
G U.S. DOD Network Information Center Vienna VA, US
H U.S. Army Research Lab Aberdeen MD, US
I Autonomica Stockholm, SE
J VeriSign Global Registry Services Herndon VA, US
K Reseaux IP Europeens - Network Coordination  Centre London, UK
M WIDE Project Tokyo, JP

These attacks resulted in periods of zero reachability for many of the root servers and an increase in packet loss approaching 10% from normal packet loss levels of less than 1%. Currently packet loss remains at approximately 4%. At the peak of the attack, average reachability for the entire DNS network dropped below 94% from normal levels near 100%. "

preludes
to 
criminal 
attacks

"Denial of Service attacks can be preludes to criminal attacks" Bruce Schneier,  Secrets & Lies: Digital Security in a Networked  World Chpt 3, page 38

Burglars come to a warehouse. They cut the connection on the alarm, hoping to trigger a response from the police. The police arrive - see nothing. Property owners representative arrives - sees nothing, everybody leaves. Later that same night, after all the authorities have retreated, the burglars (watching all the time) come back to the premises, break-in again (this time the alarm doesn't go off cause it hasn't been fixed from before) and the bad guys steal everything !!!

Schneier goes on further to describe denial of service attacks in detail in Chpt 11 of his book

from chpt 11, page 181

"In Sept 1996, an unknown hacker attacked the Public Access Networks Corporation (aka Panix) - which was a New York based internet service provider. What they did was send hello messages (SYN packets) to the Panix computers. What's supposed to happen is for the remote computer to send Panix this hello message, for Panix to respond, and then for the remote computer to continue the conversation. What the attackers did was to manipulate the return address of the remote computers, so Panix ended up trying to synchronize with computers that essentially did not exist. The Panix computers waited 75 seconds after responding for the remote computer to acknowledge the response before abandoning the attempt. The hackers flooded Panix with as many as 50 of these wake-up messages per second. This was too much for the Panix computers to handle, and they caused the computers to crash. This is called SYN flooding, and was the first publicized example of a denial of service attack against an internet host"