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g4jedi
join:2002-12-23
Escondido, CA

g4jedi

Member

[OS X] MacOS 10.5 Leopard DNS Issues

Ever since I upgraded to Leopard (and now 10.5.1) I am having what appears to be a DNS issue. Some sites load slow or not at all. When they wont load at all, I get the "network diagnostics" screen. Heck, sometimes even the Apple site wont come up for me! Has anyone else had this problem?

bbarrera
MVM
join:2000-10-23
Sacramento, CA

bbarrera

MVM

Happened to me yesterday in Safari. However Camino and Firefox and everything else was working fine so it wasn't a DNS problem. Appears to be a Safari problem. Resetting Safari didn't fix it. Logging out and logging in didn't fix it, Only way to fix it was rebooting. No problems today.

g4jedi
join:2002-12-23
Escondido, CA

g4jedi

Member

You are right. It is clearly a Safari problem. A site that cannot be found in Safari, comes up with two shakes of a lambs tail in Fire Fox! Apple clearly needs to fix this bug!

MarkyD
Premium Member
join:2002-08-20
Oklahoma City, OK

MarkyD to g4jedi

Premium Member

to g4jedi
Leopold has made me loathe Safari.

bbarrera
MVM
join:2000-10-23
Sacramento, CA

bbarrera

MVM

Yeah for about 15 minutes I was pretty pissed off at Safari and Leopold.

g4jedi
join:2002-12-23
Escondido, CA

g4jedi

Member

Yeah... it's very sporadic I have noticed. Sometimes Safari is lightning fast and sometimes slow or not loading a site at all. Firefox is sometimes slow, but at least the site always loads. While Safari is definitely flawed, Leopard has a definite DNS issues with some ISPs. I did a little Googling.

bbarrera
MVM
join:2000-10-23
Sacramento, CA

bbarrera

MVM

Install Camino if you want the best of Firefox and Safari all rolled into one browser.

Sebehk
USN Retired, 1993-2013, yvan eht nioj
Premium Member
join:2002-02-09
Pueblo, CO

Sebehk to g4jedi

Premium Member

to g4jedi
I have no issues with Safari on 10.5.1, mainly because I don't use my ISP's DNS; I use OpenDNS and it works fast!

--->Robert
8-)

bbarrera
MVM
join:2000-10-23
Sacramento, CA

bbarrera

MVM

said by Sebehk:

I have no issues with Safari on 10.5.1, mainly because I don't use my ISP's DNS; I use OpenDNS and it works fast!

--->Robert
8-)
Just wait it might happen to you, I'm running my own DNS cache and don't rely on my ISP's DNS.

In any case this is a Safari problem and NOT a dns problem. Other web browsers work fine and the problem is limited to Safari.

shavano
Even in America -- I long for America
join:2003-06-08
Dallas, TX

shavano to g4jedi

Member

to g4jedi
For a while yesterday, Safari decided it couldn't resolve dslreports.com, though Firefox, Camino and CLI had no problems.

It started after I disconnected my firewall from my cable modem for a minute and one of the thread auto-refreshes timed out.

I fooled with trying several things to get it reset for 15 minutes before giving up and restarting the Mac. Then it was fine.

rexbinary
MOD King
Premium Member
join:2005-01-26
Plano, TX

rexbinary to g4jedi

Premium Member

to g4jedi
I haven't seen any DNS issues on Safari under Leopold. I use OpenDNS as well, good stuff.

g4jedi
join:2002-12-23
Escondido, CA

g4jedi

Member

Ok I checked out Open DNS and all I can say is... WOW! Everything loads way faster now. Even in SAFARI!!!

bobrk
You kids get offa my lawn
Premium Member
join:2000-02-02
San Jose, CA

bobrk

Premium Member

How come y'all don't just use the DNS from your ISP?

g4jedi
join:2002-12-23
Escondido, CA

g4jedi

Member

I was! Open DNS just seems to work better.

bbarrera
MVM
join:2000-10-23
Sacramento, CA

1 edit

bbarrera to shavano

MVM

to shavano
said by shavano:

For a while yesterday, Safari decided it couldn't resolve dslreports.com, though Firefox, Camino and CLI had no problems.

It started after I disconnected my firewall from my cable modem for a minute and one of the thread auto-refreshes timed out.
Something similar here, but included all the other websites open in tabs (DSLreports, Gmail, etc).
said by g4jedi:

Ok I checked out Open DNS and all I can say is... WOW! Everything loads way faster now. Even in SAFARI!!!
Imagine OpenDNS but even faster (because it is on your LAN). That's what its like having a dns cache running on your LAN. One reason I'm running my own dns cache and not using my ISP's dns cache.
bbarrera

bbarrera to g4jedi

MVM

to g4jedi
I think the issue is that Safari relies on Directory Services cache (replaces lookupd), and after waking up from sleep the MacBook Pro tags www.dslreports.com as "Neg" which I *assume* means negative and that causes Safari to ignore the IP address that is in the Directory Services cache.

Here you can see that when there is a problem in Safari, the dns entry is tagged "YES" under the Neg column.
% dscacheutil -cachedump -entries host
...
...
Cache entries (ordered as stored in the cache):
 
      Category         Best Before         Last Access      Hits    Refs       TTL    Neg  DS Node
    ----------  ------------------  ------------------  --------  ------  --------  -----  ---------
...
...
          Host   11/19/07 07:56:34   11/19/07 06:59:11         2       2      3600    YES  
                     Key: h_name:www.dslreports.com ipv4:1 ipv6:1
...
...
 
And here you can see Directory Services cache in fact knows the IP address of dslreports.com
% dscacheutil -q host -a name www.dslreports.com
name: dslreports.com
alias: www.dslreports.com 
ip_address: 209.123.109.175
 
Therefore if I'm correct then there is a race condition when the MBP comes out of sleep and the network isn't available before Directory Services Cache goes out looking for the IP address. Therefore *occasionally* one or a few DNS lookups fail after waking from sleep and those are tagged Negative for 3600 seconds (one hour).

I'm reporting the issue to Apple.
bbarrera

bbarrera

MVM

Almost forgot to post the workaround.

This terminal command will fix the problem:
dscacheutil -flushcache
 
by flushing all the DNS entries in the cache and forcing new lookups.

bobrk
You kids get offa my lawn
Premium Member
join:2000-02-02
San Jose, CA

bobrk to bbarrera

Premium Member

to bbarrera
Great analysis! Good catch!