CNIT 342 Exam 2 Review - DNS And
Packet Filtering Questions And Answers
With Verified Solutions 100% Correct!!!
What is the purpose of name resolution? - ANSWER✔✔- map station names back
to IP addresses
- utilizes hosts files
What is DNS? - ANSWER✔✔- domain name system (IETF standard)
- hierarchical naming system
True/False: DNS is traditionally a static approach. - ANSWER✔✔true
- hard-coded list of names and IP address
- assumes station always has same IP
- does NOT work well with DHCP
Describe the DNS name space structure. -
ANSWER✔✔host.subdomain(s).top_level_domain
- each level unique to next higher level
Up to how many levels of domains are allowed? - ANSWER✔✔127 levels
(separated by dots)
Up to how many characters per domain are allowed? - ANSWER✔✔63 characters
In which direction is authority handed down in the DNS name space structure? -
ANSWER✔✔- authority is handed down from top-level to lower levels
Which organization manages the top-level (root) domains? - ANSWER✔✔-
InterNIC
What are some examples of top-level (root) domains managed by InterNIC? -
ANSWER✔✔.edu, .com, .gov, .mil, .org, country codes, .biz, .info, .name, .pro,
.aero, .coop, .museum
, Who holds the authority over lower-level domains and all created sub-domains? -
ANSWER✔✔- holder of a second level domain
- sub-domains can be created at will
What differentiates a domain from a zone? - ANSWER✔✔- domains map back to
names used in DNS hierarchy (purdue.edu, net.lcl)
- zones represent the METHOD used to manage domains
What is the purpose of a zone? - ANSWER✔✔- represents the method used to
manage domains
- zones are authoritative for a domain or sub-domain
- sub-domains can be given their own zone or stored within a single zone
At least how many authoritative DNS servers must each second-level domain
have? - ANSWER✔✔- at least two authoritative DNS servers
What is an authoritative DNS server? - ANSWER✔✔- contains the actual DNS
entries
- must be up 24/7
- address for server listed in next higher level's configuration
- root server must know about all second-level domain servers
How many root name servers are spread around the world? - ANSWER✔✔- 13
- named a, b, c....
Describe the forward name resolution process. - ANSWER✔✔example:
- end node (resolver) in tech.purdue.edu domain asks the local Purdue DNS server
for IP address for www.slashdot.org
- called a recursive query
- name server is obligated to supply an answer
- the local name server isn't authoritative for slashdot.org to it goes and finds the
answer from an authoritative name (consults root hints file, asks .org root server)
- root server is only obligated to point local name server in right direction (lowers
load on root server)
- root server points local server to authoritative server for slashdot.org
- local name server contacts slashdot.org and asks for answer
- slashdot.org server IS authoritative, so it responds with answer
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