DNS info and troubleshooting

[Dawiz]

Hello everyone. I am currently learning about DNS and troubleshooting techniques for a job I am hoping to get. I know very little so please be easy on me I need to know the following
1. finding authoritative name servers
2. how to use nslookup(or dig) to look up specific zone records ( A, and/or MX ) from the authoritative name servers
3. I also need to know about DNS caching and why its important to look up DNS answers from the authoritative name server.

if you could help me out with any of these, it would be greatly appreciated. thankyou.

 

[Jonius]

Solution

The nslookup command can be used to find various details relating to DNS including
>IP addresses of a particular computer,
>MX records for a domain or the NS servers of a domain - all using DNS lookups.

I believe you know the meaning of nslookup --"name server lookup".

A more modern alternative to nslookup is the dig program, they all shipping with BIND.

Some subcommands for nslookup are:
server NAME (where NAME is the name or ip address of the dns server you wish to query). It is not always possible to query a specific dns server as often dns queries are blocked to prevent denial of service attacks

set type=NAME (where NAME is the type of record you would like to look at. For example set type mx will give you the mail records)

Example on how its used just type

$ nslookup www.google.com