How did the attacker accomplish this hack?

Joseph was the Web site administrator for the Mason Insurance in New York, who’s main Web site was located at www.masonins.com. Joseph uses his laptop computer regularly to administer the Web site. One night, Joseph received an urgent phone call from his friend, Smith. According to Smith, the main Mason Insurance web site had been vandalized! All of its normal content was removed and replaced with an attacker’s message ”Hacker Message: You are dead! Freaks!”

From his office, which was directly connected to Mason Insurance’s internal network, Joseph surfed to the Web site using his laptop. In his browser, the Web site looked completely intact. No changes were apparent. Joseph called a friend of his at his home to help troubleshoot the problem. The Web site appeared defaced when his friend visited using his DSL connection. So, while Smith and his friend could see the defaced page, Joseph saw the intact Mason Insurance web site. To help make sense of this problem, Joseph decided to access the Web site using his dial-up ISP. He disconnected his laptop from the corporate internal network and used his modem to dial up the same ISP used by Smith. After his modem connected, he quickly typed www.masonins.com in his browser to reveal the following web page:

H@cker Mess@ge:

Y0u @re De@d! Fre@ks!

After seeing the defaced Web site, he disconnected his dial-up line, reconnected to the internal network, and used Secure Shell (SSH) to log in directly to the Web server. He ran Tripwire against the entire Web site, and determined that every system file and all the Web content on the server were intact.

How did the attacker accomplish this hack?

A.
ARP spoofing

B.
SQL injection

C.
DNS poisoning

D.
Routing table injection

Explanation:
External calls for the Web site has been redirected to another server by a successful DNS poisoning.