A routing table is a set of rules, often viewed in table format that is used to determine where data packets traveling over an Internet Protocol (IP) network will be directed. All IP-enabled devices, including routers and switches, use routing tables. Each packet contains information about its origin and destination. When a packet is received, a network device examines the packet and matches it to the routing table entry providing the best match for its destination. The table then provides the device with instructions for sending the packet to the next hop on its route across the network. Thus the security consultant can use the global routing table to get the appropriate information.
Incorrect Answers:
B: Calling the regional Internet registry will not provide you with the correct information.
C: The telecom billing information will not have information as to whether the legacy backup may have Internet connections on the network.
D: DNS server queries are used to resolve the name with each query message containing a DNS domain name, a specified query type and a specified class. This is not what the security consultant requires.
References:
https://technet.microsoft.com/en-us/library/cc958823.aspx
Gregg, Michael, and Billy Haines, CASP CompTIA Advanced Security Practitioner Study Guide, John Wiley & Sons, Indianapolis, 2012, pp. 60-66

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