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Specific websites going slow - 31.Jan.2008 6:37:00 AM

xsproltd

Posts: 10
Joined: 21.Aug.2007
Status: offline

Hello all,

My client is using an ISA 2004 solution with 60-70 Web Proxy clients.

The problem they are having is that the sites they access most frequently are slow to load, but other less frequently accessed sites open up really fast.

I thought perhaps this might be a DNS or Cache related issue?

If anyone could give me some pointers?

I have done plenty of prelimanary testing, such as making sure the server is not overloaded such as processor, memory consumption.
There is plenty of hard drive space, and the cache is working fine.

They have multiple static IPs on the router itself, and the team that is not going through ISA, can access the sites fine, so i know this is not related to the router or their Internet Bandwidth.

If anyone can give me some ideas, i would be grateful

Regards

Post #: 1

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RE: Specific websites going slow - 31.Jan.2008 8:32:24 AM

abqtech

Posts: 216
Joined: 9.Mar.2004
Status: offline

what can you tell us about the slow loading sites:

Are they SSL?
What FQDN's are they?

(in reply to xsproltd)

Post #: 2

RE: Specific websites going slow - 31.Jan.2008 9:14:17 AM

xsproltd

Posts: 10
Joined: 21.Aug.2007
Status: offline

The sites are not SSL.

The FQDN of one of the sites is mysheffieldjobs.co.uk

Externally it loads quite fast. Internally it can take between 3-4 seconds to appear.

(in reply to abqtech)

Post #: 3

RE: Specific websites going slow - 31.Jan.2008 10:40:01 AM

Rotorblade

Posts: 899
Joined: 27.Feb.2007
Status: offline

To Add:

Do you have many access rules configured or doing any type of destination set blocking?

Third party App/filters installed?

DNS could be an issues depending on how you have it configured.

Is PMTU discovery enabled on the ISA? http://support.microsoft.com/kb/902347

HTH

RB

_____________________________

David Melvin
Ohio
MCSE: Security 2003, MCSA:Security 2003

(in reply to xsproltd)

Post #: 4

RE: Specific websites going slow - 31.Jan.2008 10:42:44 AM

xsproltd

Posts: 10
Joined: 21.Aug.2007
Status: offline

Hi,

Yes there is blocking to certain website destinations as part of the corporate policy.
There are about 9 Rules that are in place on the server in total.

No third party appl installed.

I'll check out the KB article. Thanks

(in reply to Rotorblade)

Post #: 5

RE: Specific websites going slow - 31.Jan.2008 11:32:14 AM

Rotorblade

Posts: 899
Joined: 27.Feb.2007
Status: offline

Good,

Try disabling the blocking rules to see if anything changes. Destination sets can and will slow you down and depend on heavily DNS resolution. DNS may be an issue if you�re doing a lot DNS forwarder chaining.

HTH

RB

_____________________________

David Melvin
Ohio
MCSE: Security 2003, MCSA:Security 2003

(in reply to xsproltd)

Post #: 6

RE: Specific websites going slow - 31.Jan.2008 12:50:26 PM

abqtech

Posts: 216
Joined: 9.Mar.2004
Status: offline

you may want to modify your ISA server caching (and CARP if you're using it) by creating a domain name set with the domain(s) that you want to exclude from the ISA Server Cache and CARP. And then add that domain name set as an execption to your Cache/CARP rules. I'd just add one of the sites that you know is running slow into the domain name set, and see if it improves the performance. Also Rotorblade gave some really good things to check as well.

(in reply to Rotorblade)

Post #: 7

RE: Specific websites going slow - 1.Feb.2008 5:05:51 AM

xsproltd

Posts: 10
Joined: 21.Aug.2007
Status: offline

Hi,

Thank you for your response. I didnt quite follow what you mean?
I hope you dont mind, but could you please elaborate a little further?

Sorry to be a pain

regards

(in reply to abqtech)

Post #: 8

RE: Specific websites going slow - 1.Feb.2008 1:36:42 PM