Hi Amos, Thanks a lot for your detailed reply. I have disabled IPv6 on my Centos 6.4 squid server by setting: net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 in my sysctl.conf, rebooted the server but still I see AAAA records are being sent out by squid! Regards, Firas ----- Original Message ----- From: Amos Jeffries <squid3@xxxxxxxxxxxxx> To: squid-users@xxxxxxxxxxxxxxx Cc: Sent: Saturday, July 27, 2013 8:50 AM Subject: Re: Squid Sending AAAA DNS queries On 27/07/2013 2:40 a.m., Golden Shadow wrote: > Hello squid-users, > > My squid is sending AAAA DNS queries, while IPv6 is not enabled on my network. How can I prevent squid from sending AAAA DNS queries? I only found dns_v4_first squid directive, which does not completely disable AAAA queries. The current supported release of Squid will not send DNS AAAA queries if IPv6 is not available. Seeing that behaviour means your Squid is detecting that IPv6 *is* available and partially operating, at least on the machine running Squid. There is no harm in querying AAAA records - the current Squid do parallel (Happy-Eyeballs) DNS lookups with that dns_v4_first flag to ensure that on networks such as yours IPv4 has priority over IPv6 (avoiding the connection delays and any other issues your lack of IPv6 network support causes). If your DNS lacks capacity for Squid's lightweight lookup style now you are already screwed, DNSSEC for example has multiple layers of lookups with huge packets involved. PS. That DNS traffic also helps provide both you and the destination site owners a reliable indicator for how much IPv6 demand needs to be expected and catered for if either of you turn it on right now. For example the A vs AAAA result counters in cachemgr "idns" report to see what % of your HTTP capacity load an IPv6 tunnel would need to cater for if you setup one from the Squid machine. Amos
