i don't have ipv6 and only using ipv4. when i ping resolve ipv6 not ip

[MonkeyBear007]

i don't have ipv6 and only using ipv4. when i ping resolve ipv6 not ipv4

Lab-Hub#ping yahoo.com
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:4998:24:120D::1:0, timeout is 2 seconds:

% No valid route for destination
Success rate is 0 percent (0/1)
Lab-Hub#

[MHM Cisco World]

Debug ip dns 

Share this 

MHM

[pieterh]

a "normal" domain-lookup should retreive both IPV4 and IPV6 adresses (multiple)

C:\Users\>nslookup yahoo.com
Server: UnKnown
Address: x.x.x.x [ my forwarding dns-server]

Non-authoritative answer:
Name: yahoo.com
Addresses: 2001:4998:24:120d::1:0
2001:4998:24:120d::1:1
2001:4998:124:1507::f000
2001:4998:124:1507::f001
2001:4998:44:3507::8000
2001:4998:44:3507::8001
74.6.143.25
74.6.143.26
74.6.231.21
98.137.11.163
98.137.11.164
74.6.231.20

the dns server you use in your lab may have cached only the first returned adresss from the external dns servers
and presents this to your switch
the command mentioned by @MHM Cisco World gives a more detailed view of the dns-resolving than simple nslookup

[paul driver]

Hello

---

C:\Users\>nslookup yahoo.com
Server: UnKnown
Address: x.x.x.x [ my forwarding dns-server]

---

This is the server that is resolving  the both DNS A and Quad A resolution for that domain, not your pc /router/switch, even though most probably you have ipv6 enabled (default) on your pc

I assume this is your ISP supplied dns what you home network is using or forwarding towards

Open a cmd prompt on your pc it will show you if you also have both ipv4/ip6 enabled, by default you should have
ipconfig /all

[Jonatan Jonasson]

since it seems you're doing this on a cisco ios device.

If you have any interface configured with an IPv6 address, then IPv6 is enabled on this device and it will try and prefer IPv6 if DNS responds to both AAAA and A queries. 

So do this command: show ipv6 interface brief

And check if any of the interfaces include an IPv6 address, and remove if necessary.

This can happen even if you have no IPv6 route installed, and you can easily test this on many devices just by adding a ULA IPv6 address to a vlan interface and then try to ping yahoo.com

[wajidhassan]

Hi @MonkeyBear007 ,

The issue you're seeing happens because the DNS is resolving yahoo.com to an IPv6 address (2001:4998:...), and your router is trying to use that by default — even though IPv6 isn't configured.

To fix this, you can either:

1. Manually specify IPv4 ping:
   Use ping ip yahoo.com instead of just ping yahoo.com — this forces the router to use IPv4.

2. Disable IPv6 (optional):
   If you don't plan to use IPv6 at all, you can disable it globally:

   Router(config)# no ipv6 unicast-routing

Hope this clears it up!