Chapter 7

Many business computers have three distinct and worldwide unique identifiers. What are they?

Which DNS record verifies the signature of the DNS records for an authoritative name server?

Describe the process of client mapping, by which some part of the DNS infrastructure would identify a content server that is close to the client that issued the DNS query. Explain any assumptions involved in determining the location of the client.

Consider a situation in which a cyberterrorist makes all the DNS servers in the world crash simultaneously. How does this change one's ability to use the Internet?

Explain the advantages and disadvantages of using TCP instead of UDP for DNS queries and responses.

Assuming that caching behavior for DNS lookups is as normal and DNS is not encryp-ted, which of the following parties can see all of your DNS lookups from your local device? If DNS is encrypted with DoH or DoT, who can see the DNS lookups?

Nathan wants to have an original domain name and uses a randomized program to generate a secondary domain name for him. He wants to register this domain name in the com generic domain. The domain name that was generated is 253 characters long. Will the com registrar allow this domain name to be registered?

Can a machine with a single DNS name have multiple IP addresses? How could this occur?

The number of companies with a Web site has grown explosively in recent years. As a result, thousands of companies are registered in the com domain, causing a heavy load on the top-level server for this domain. Suggest a way to alleviate this problem without changing the naming scheme (i.e., without introducing new top-level domain names). It is permitted that your solution requires changes to the client code.

Some email systems support a Content Return: header field. It specifies whether the body of a message is to be returned in the event of nondelivery. Does this field belong to the envelope or to the header?