f. Describe how an attacker can use whois databases and the nslookup tool to perform reconnaissance on an institution before launching an attack. g. Discuss why whois databases should be publicly available. P19. In this problem, we use the useful dig tool available on Unix and Linux hosts to explore the hierarchy of DNS servers. Recall that in Figure 2.21, a DNS
server higher in the DNS hierarchy delegates a DNS query to a DNS server lower in the hierarchy, by sending back to the DNS client the name of that lower-level DNS server. First read the man page for dig, and then answer the following questions. a. Starting with a root DNS server (from one of the root servers[am].rootservers. net), initiate a sequence of queries for the IP address for your department’s Web server by using dig. Show the list of the names of DNS servers in the delegation chain in answering your query.b. Repeat part a) for several popular Web sites, such as google.com, yahoo.com, or amazon.com.
P21. Suppose that your department has a local DNS server for all computers in the department. You are an ordinary user (i.e., not a network/system administrator). Can you determine if an external Web site was likely accessed from a Computer in your department a couple of seconds ago? Explain.
Q3. Identify the 13 root name servers of the Internet via dig command utility and show your command options and query outputs with root server names, IP addresses and related info in verbose mode;
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- Fall '13
- E-mail, IP address, Domain Name System, DNS servers