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IPv6 DNS lookup instead of IPv4

OrkhanRustamli
Beginner
Beginner

Hey All,

I have 9500 series Switches which is facing the firewall and plays the DNS Proxy role for clients and everything is perfect. What is the problem I want to renew license with CSSM and therefore it needs to contact tools.cisco.com. I have tested and the switch has ip connectivity to internet, ping works. But the problem is when I try to telnet tools.cisco.com 443 I see that it tries to contact IPv6 address. I tested several other domain names and all are the same with IPv6. I have disabled IPv6 unicast-routing globally, but it does not help.

 

telnet tools.cisco.com 443
Trying 2001:420:1201:5::A, 443 ...
% Destination unreachable; gateway or host down

 

Any help is appreciated.

 

 

8 Replies 8

MatsR
Beginner
Beginner

Hi,

 

Did you solve this?

I have this excact same issue on a C1100 router

 

 

BR

Mats

 

Hi,

 

    First try configuring this: "call-home/http resolve-hostname ipv4-first", clear your DNS cache and see if it works now; if still not, try rebooting; if still not, hardcode the IPv4 address in the call-home URL (instead of the name), get the job done and raise a TAC case.

 

Regards,

Cristian Matei.

M@rco
Beginner
Beginner

set "no ipv6 enable" on the DNS-facing interface

That doesn't work!

Did anybody work out the answer to this?

Looks like there's an answer here: https://community.cisco.com/t5/switching/disable-aaaa-dns-lookups-on-non-ipv6-router/td-p/3413517

- Disable ipv6 on all interfaces.

Hello,

 

not sure if you already posted this in another thread ? I cannot reach the site at all...I wonder if the site is up...

Seems to work for me:

TEST#ping tools.cisco.com
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 72.163.4.38, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 112/113/116 ms

Hello,

 

ping works, but nothing else. I cannot reach the site on any port...

Works for me - maybe a local ACL/firewall problem.

TEST#telnet tools.cisco.com 443 /ipv4
Trying tools.cisco.com (173.37.145.8, 443)... Open

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