Module 4 Flashcards
DNS
Domain Name System. A global and highly distributed network service that resolves strings of letters into IP addresses
Steps of Recursive Name Resolution
- Contact Root Server, which will return the TLD server that should be queried
- Contact the TLD server, which will respond with a redirect to authoritative server.
- Contact the authoritative server for that specific domain name
Name Resolution
The process of using DNS to turn a domain name into an IP address.
5 Types of DNS servers
- Caching name servers
- Recursive name servers
- Root name servers
- TLD Name servers
- Authoritative Name servers
Caching Name Server
Purpose is to store known domain name lookups for a certain amount of time
Recursive name servers
Performs full DNS resolution requests to discover correct IP for domain name.
Domain Name TTL
A value in seconds that can be configured by the owner of a domain name for how long a name server is allowed to cache an entry before it should discard it and perform a full resolution again
How many root servers are there and how are they distributed
13 distributed by across the globe through anycast, a technique used to route traffic to different destinations depending on factors like location, congestion, or link health
TLD
Top level domain. Represents the top of the hierarchical DNS name resolution system. it is the last part of a domain like .com, or .biz
What protocol does DNS use
UDP. DNS request can fit into a single UDP datagram.
Which port is DNS request sent to on the Caching server
53
DNS Resource Record Types
- A record
- AAAA record
- CNAME record
- MX record
- SRV record
- TXT record
A record
Used to point to certain domain name at a certain IPv4 IP address
Round Robbin
Iterating over a list of items one by one in an orderly fashion
Quad A record
Used to point to certain domain name at a certain IPv6 IP address
CNAME Record
Canonical Name Record.
Ensures that both microsoft.com and www.microsoft.com resolves to the same ip