Solved: Name Resolving does not work on ESXI 5.5 update2

yuvalwoll · ‎10-22-2017

Hi for some strange reason the name resolution on my ESXI server does not work

I've set up the same DNS servers and search suffixes as other servers

this only happens in hosts that are esxi 5.5

on ESXI 6 servers that are running this issue does not happen

i've checked with "nc -zu "ip address" 53 and i get connection establish so i'ts not a firewall issue

the funny thing is even when points the dns quary to the DNS server itself it doesnot work:

nslookup "DNS quary" "DNS server ip address"

i get "nslookup: can't resolve "

i've also tried restarting the DNS daemon to clear the cache and still doesnt work

i've also ran "vmkping -I" to force the dns quary to go out the right interface that didn't help either

yuvalwoll · ‎10-24-2017

Ok i found out the root of the problem ,

after performing TCP dump of the vmkernel

"tcpdump-uw -i vmk0 port 53 -s0"

I've discovered that every dns quary that ESXI 5.5U2 does it will only use the primary dns server on i'ts list

if the primary dns server responds with "Record not found" it will not proceed with the following dns servers

so the only option is to configure conditional forwarding on the dns server

I've verified that i have all the dns servers listed using esxcli and DCUI

they even appear in /etc/resolve.conf

admin · ‎10-22-2017

Does this help?

if you found my answer to be useful, feel free to mark it as Helpful or Correct.

yuvalwoll · ‎10-23-2017

thank for taking your time to answer,

i've already tried that KB it still doesn't work

i think the root of the issue is the fact that our management VMKernel is on a different subnet than the DNS server

i know this shouldn't be a problem and also nc works so i'ts not a firewall issue but that the only thing i can think of that is different that

other ESXI servers that DNS resolving works on them.

either that or a bug in ESXI 5.5 update 2

yuvalwoll · ‎10-24-2017