Firefox Loses DNS in F10 (also: UDP checksum errors for DNS queries)

[Andre Costa]

Hi Paul,

On Tue, Dec 2, 2008 at 10:10, Paul Black
<paul+fedora at saturnine.org.uk<paul%2Bfedora at saturnine.org.uk>
> wrote:

> 2008/12/2 Andre Costa wrote:
>
>> Actually, is this a problem at all or can I safely ignore this?
>>
>
> As Wireshark suggested, this is happens the NIC calculates the checksums
> for the packet. Since the HW is doing this, the SW doesn't bother, hence the
> wrong value that appears to be in the outgoing packet. You would need to
> verify at the receiving end whether there was an actual problem but this is
> unlikely to be the case.
>
>
Thks, so it's probably nothing to worry about.

I digged even further and found out that Google-related queries (GMail,
GReader etc.) are returning very short TTL values, as can be seen by the
wireshark capture snippet below:

    Answers
        www.google.com: type CNAME, class IN, cname www.l.google.com
            Name: www.google.com
            Type: CNAME (Canonical name for an alias)
            Class: IN (0x0001)
            Time to live: 10 hours, 31 minutes, 12 seconds
            Data length: 18
            Primary name: www.l.google.com
        www.l.google.com: type A, class IN, addr 74.125.77.99
            Name: www.l.google.com
            Type: A (Host address)
            Class: IN (0x0001)
            Time to live: 1 minute, 50 seconds
            Data length: 4
            Addr: 74.125.77.99
        www.l.google.com: type A, class IN, addr 74.125.77.147
            Name: www.l.google.com
            Type: A (Host address)
            Class: IN (0x0001)
            Time to live: 1 minute, 50 seconds
            Data length: 4
            Addr: 74.125.77.147
[...]

(first one is www.google.com, which has a TTL of 1 day)

I bet this is why no local DNS cache can help with Google addresses since
they expire so quickly. Weird thing is that, on this short monitoring I did
(a couple of minutes only), none of the Google sites (aside from the main
sites such as www.google.com and mail.google.com) had a TTL > 5min. Has this
always been this way?

Regards,

Andre
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/fedora-list/attachments/20081202/974e6031/attachment-0001.htm>