DNS Resolution

Antonino89

Member
Jul 13, 2017
76
1
6
31
Hi guys,,

currently i have a problem with all of my server:

I can ping public IP adress but i'm not able to ping their hostname.

ping 8.8.8.8 is OK
ping Google.it is NOT OK.

my resolv.conf :

root@Server1:/etc# more resolv.conf

search proxmox
nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 192.168.100.1


Any suggestions?

Thanks :)

 

pabernethy

Member
Aug 1, 2017
162
14
18
It's time to dig then ;)
Code:
$ dig google.it   

; <<>> DiG 9.10.3-P4-Debian <<>> google.it
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9377
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4000
;; QUESTION SECTION:
;google.it.            IN    A

;; ANSWER SECTION:
google.it.        133    IN    A    172.217.21.227

;; Query time: 1 msec
;; SERVER: 192.168.2.121#53(192.168.2.121)
;; WHEN: Wed Aug 09 17:13:36 CEST 2017
;; MSG SIZE  rcvd: 54
It tells you where you received the answer from in the SERVER line. If you don't get an answer from one of your nameservers you can force using them with
Code:
$ dig @8.8.8.8 google.it
Also I assume you already rebooted after entering that config or, at the very least, restarted the network.
 

Antonino89

Member
Jul 13, 2017
76
1
6
31
Yes, reboot was done.


root@Server1:~# dig google.it

; <<>> DiG 9.10.3-P4-Debian <<>> google.it
;; global options: +cmd
;; connection timed out; no servers could be reached
root@Server1:~# dig @8.8.8.8 google.it

; <<>> DiG 9.10.3-P4-Debian <<>> @8.8.8.8 google.it
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached


Problem, still remain...
 

pabernethy

Member
Aug 1, 2017
162
14
18
Can you query the local DNS server (assuming you have at least a local DNS cache available)?
Is there a router or firewall on the network that might block outgoing DNS requests?
 

Antonino89

Member
Jul 13, 2017
76
1
6
31
Can you query the local DNS server (assuming you have at least a local DNS cache available)?
Is there a router or firewall on the network that might block outgoing DNS requests?

root@Server1:~# ping 10.216.110.108 <------ Local DNS
PING 10.216.110.108 (10.216.110.108) 56(84) bytes of data.
64 bytes from 10.216.110.108: icmp_seq=1 ttl=127 time=2.54 ms
64 bytes from 10.216.110.108: icmp_seq=2 ttl=127 time=1.24 ms
64 bytes from 10.216.110.108: icmp_seq=3 ttl=127 time=1.05 ms
64 bytes from 10.216.110.108: icmp_seq=4 ttl=127 time=1.01 ms
64 bytes from 10.216.110.108: icmp_seq=5 ttl=127 time=1.50 ms
^@64 bytes from 10.216.110.108: icmp_seq=6 ttl=127 time=1.18 ms

64 bytes from 10.216.110.108: icmp_seq=7 ttl=127 time=1.14 ms

64 bytes from 10.216.110.108: icmp_seq=8 ttl=127 time=1.10 ms
^Z
[1]+ Stopped ping 10.216.110.108


root@Server1:~# dig @10.216.110.108 google.it

; <<>> DiG 9.10.3-P4-Debian <<>> @10.216.110.108 google.it
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9690
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4000
;; QUESTION SECTION:
;google.it. IN A

;; ANSWER SECTION:
google.it. 299 IN A 172.217.16.163

;; Query time: 27 msec
;; SERVER: 10.216.110.108#53(10.216.110.108)
;; WHEN: Thu Aug 10 10:19:28 CEST 2017
;; MSG SIZE rcvd: 54
 

pabernethy

Member
Aug 1, 2017
162
14
18
Looks like your firewall is blocking outgoing DNS requests. So either talk to the network administrator, if you absolutely need to use external DNS. Or just use the local DNS.
 

Antonino89

Member
Jul 13, 2017
76
1
6
31
Looks like your firewall is blocking outgoing DNS requests. So either talk to the network administrator, if you absolutely need to use external DNS. Or just use the local DNS.

Thanks. Solved.

I will use the internal DNS.

Antonino
 

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