| 1: | What is the one alternative for name resolution that doesn't use DNS? |
| A1: | Answer: You can put a local host file on each TCP/IP host. |
| 2: | What does DNS stand for? |
| A2: | Answer: Domain Name System |
| 3: | Imagine that Lenny uses a PC inside the fredsco.com domain. Lenny opens a browser and tries to browse http://www.fredsco.com. His PC is configured to use DNS. How many DNS requests will Lenny's PC likely send before he gets a response to a request for host name www.fredsco.com? |
| A3: | Answer: Lenny's PC will send one request to the DNS server that he has configured. |
| 4: | Imagine that Lenny uses a PC inside the fredsco.com domain. Lenny opens a browser and tries to browse http://www.example.com. His PC is configured to use DNS. How many DNS requests will Lenny's PC likely send before he gets a response to a request for host name www.example.com? |
| A4: | Answer: Lenny's PC will send one request to the DNS server that he has configured and expect a response from that DNS server. Lenny's PC will not send a request to the DNS server for domain example.com; instead, Lenny's DNS server will handle the rest of the work. |
| 5: | Imagine that Lenny uses a PC inside the fredsco.com domain. Lenny opens a browser and tries to browse http://www.example.com. Imagine that his PC gets a DNS response that www.example.com's IP address is 192.0.33.166. When Lenny's PC sends a packet to that web server, does the PC include the destination IP address of 192.0.33.166 in the IP packet header, or the destination name of www.example.com in the IP packet header, or both? |
| A5: | Answer: The IP packet header does not include a place for a host name. Lenny does put the destination IP address into the header, so that this host, along with any intermediate routers, will forward the packet correctly to that web server. |
| 6: | State whether you agree with the following statement and why: "Each TCP/IP host refers to its DNS server using a well-known IP address 0.4.1.1." |
| A6: | Answer: Disagree. Each TCP/IP host does need to know the IP address of its respective DNS servers, but it must know the actual IP address of the server. 0.4.1.1 is not a legal IP address, and the DNS server for each domain will have a different IP address. There is no standard IP address for a DNS server. |
| 7: | Given a name like www.example.com, identify the likely domain name, and using that example, define the term "domain name." |
| A7: | Answer: The domain name would be "example.com." It is likely that all names that end in "example.com" are resolved by an authoritative DNS server controlled by the same company that registered to use "example.com" as a domain name. A domain name simply identifies the authority, organization, or company that controls all names that end in that suffix. |
| 8: | When a client inside one company tries to browse a web server in another company, using a name, describe in general terms how the authoritative name server for the web server name is found. |
| A8: | Answer: The user's host asks its DNS server to resolve the name. The local DNS doesn't know the name because the name is in another domain. The local DNS asks a root name server for help. The root refers the local DNS to another DNS server, which might be the authoritative DNS for that name. The local DNS now asks this newly discovered DNS server for help. That DNS server would return the correct IP address to the original IP host. |
| 9: | State whether you agree with the following statement and why: "When a user who is configured to use DNS opens a web browser and types in http://www.example.com, the next IP packet that he sends is to the web server." |
| A9: | Answer: Disagree. The first packet would be the DNS resolution request to the DNS server. After the host learns the IP address of that web server, it will send packets to the server. |
