Linux DNS Resolution

Question 1

/etc/hosts

Answer 1

Text file containing local hosts entry to loop back address in ipv4 or v6. Can also be used to map other hostname to IP address.

Question 2

/etc/hostname

Answer 2

Used for system hostname. Hostnamectl file write system hostname to file.

Question 3

/etc/resolv.conf

Answer 3

IP address of DNS name servers host will use for name resolution.

Question 4

/etc/nsswitch.conf

Answer 4

Among others, used to determine order of name resolution.

Question 5

host

Answer 5

Resolve down names to IP address. When querying outside, obtain email resolution with numbers for priority (mail exchange records.)

Question 6

dig

Answer 6

Query’s DNS servers for specific DNS records. @ to reference specific DNS server for website.
-t: DNS record type. Ex: MX for mail server, A for address record, any for any records possible.

Question 7

getent

Answer 7

Directly queries /etc/nsswitch.conf file and database locations.