DNS

Question 1

DNS: Domain Name System

Answer 1

converts human-readable names to IP addresses.

- fundamental support protocol for internet and computer networks

Question 2

How is a DNS name broken down?

Answer 2

1. top level domain (TLD)
2. domain part
3. subdomain part (if applicable)
4. host part

Question 3

what is the dns structure of: www.sub.domain.com

Answer 3

www = host
sub = subdomain
domain = domain
com = top level domain (TLD)

Question 4

resolvers

Answer 4

performs name resolution

• servers that contact TLD DNS servers
• servers provided by ISP or OpenDNS or GoogleDNS

Question 5

DNS Resolution Algorithm

Answer 5

1. resolver contact root name server (has info on TLD)
2. ask TLD name server about domain resolver is looking for
3. if subdomains = step 2 is performed again
4. resolver asks for name resolution of host part

Question 6

How can a resolver know how to contact a root name server?

Answer 6

IP addresses of the root servers are hardcoded in the config of the resolver. SysAdmins keep the list updated or else the resolver would not be able to contact the root server!