Browser speed issue

Hal Burgiss hal at burgiss.net
Sat Jun 5 22:43:08 UTC 2010


On Sat, Jun 5, 2010 at 2:01 PM, Dick Dowdell <dick.dowdell at gmail.com> wrote:
> Actually, the DNS servers are provided by Verizon FIOS and are working fine
> for the browsers on Win 7.  I'm getting a "Looking up <host-name>" message
> for each host referenced by the page. I'm not a network expert, but I am an
> expert network programmer.  I expect the local IP stack to cache IP
> addresses after DNS searches.  That doesn't seem to be happening.

I've not seen the "local IP stack" caching DNS on Linux and I've been
using it for 12 years now. Perhaps there is something new going on,
but if so I think DNS caching by any local desktop machine OS to be a
bad idea. Much better to have a real service handle this (locally or
on a nearby net). That being said, if the servers are known to be
good, and you get that kind of issue, then something system level is
going on to slow things down. But I don't think its caching per se or
lack thereof,  for reason mentioned above.

Another possibility is that Windows7 is indeed caching DNS and it is
obscuring a slow server response. Maybe. Its easy to benchmark this on
Linux. Try, in a terminal (requires installing one of the BIND
packages, probably bind-utils or somesuch):

$ time host google.com
google.com has address 74.125.95.105
google.com has address 74.125.95.99
google.com has address 74.125.95.103
google.com has address 74.125.95.104
google.com has address 74.125.95.147
google.com has address 74.125.95.106
google.com mail is handled by 300 google.com.s9b1.psmtp.com.
google.com mail is handled by 100 google.com.s9a1.psmtp.com.
google.com mail is handled by 200 google.com.s9a2.psmtp.com.
google.com mail is handled by 400 google.com.s9b2.psmtp.com.

real    0m0.061s
user    0m0.004s
sys     0m0.008s

The above is a non locally cached response from my ISP (using Ubuntu
9.10 on my desktop).

Below is cached response on my work desktop (with DNS caching on the
local LAN), also 9.10:

$ time host google.com
google.com has address 74.125.95.105
google.com has address 74.125.95.147
google.com has address 74.125.95.99
google.com has address 74.125.95.104
google.com has address 74.125.95.103
google.com has address 74.125.95.106
google.com mail is handled by 200 google.com.s9a2.psmtp.com.
google.com mail is handled by 300 google.com.s9b1.psmtp.com.
google.com mail is handled by 400 google.com.s9b2.psmtp.com.
google.com mail is handled by 100 google.com.s9a1.psmtp.com.

real    0m0.015s
user    0m0.008s
sys     0m0.004s

I would consider either acceptable, though obviously .015s whens a foot race.

If you get a real slow response, you might also make sure the local
system isn't real busy by looking at the load. If there is high load
for whatever reason (CPU or IO), then that impacts things, of course.

Cheers.

-- 
Hal




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