Host is not resolved but connecting via telnet, can somebody explain how?

Asked Jul 22 '20 at 12:38

Active Jul 22 '20 at 12:47

Viewed 458 times

In aws ec2 instance, rds host name is not resolved by ping or nslookup but it is still able to reach via telnet or nc how ?

~# nslookup xxxx.rds.amazonaws.com
nslookup: can't resolve '(null)': Name does not resolve

but in nc

~# nc -vv  xxxx.rds.amazonaws.com 3306
xxxx.rds.amazonaws.com (xxx.xx.xx.xxx:3306) open

Can somebody explain me How this is possible ?

edited Jul 22 '20 at 12:47

asked Jul 22 '20 at 12:38

Smart Athiyas

Your `nslookup` seems broken. What OS is this? – Michael Hampton Jul 22 '20 at 12:51
ec2 instance : ubuntu 16.04 – Smart Athiyas Jul 22 '20 at 13:00
but other hosts are resolved by nslookup – Smart Athiyas Jul 22 '20 at 13:02
A simple guess, does nc use alternative method than dns to resolve the hostname ? I ask, as on windows in exemple iexplore default to use netbios name resolution before using the dns's one. – yagmoth555 Jul 22 '20 at 13:34
Local `/etc/hosts` file? – Krackout Jul 22 '20 at 14:13
1

RDS doesn't respond to ping, but nslookup should work. I wonder if this is a typo? Cannot resolve (null) suggests a problem with your nslookup. – Tim Jul 22 '20 at 17:35

0 Answers0