Browser Is Slow to Respond When You Use an Automatic Configuration Script (315810)
The information in this article applies to:
- Microsoft Internet Security and Acceleration Server 2000
- Microsoft Proxy Server 2.0
This article was previously published under Q315810 SYMPTOMS When you configure your Web browser to use either the
Automatically detect settings setting or the Use
automatic configuration script setting in the browser's Web proxy
settings, you may experience a long delay before Web pages start to load (the
delay is usually between 5 to 40 seconds). These symptoms only occur
when you use the following configuration:
- The Web proxy server is running either Proxy 2.0 or
Internet Security and Acceleration (ISA) Server.
- You use the default automatic configuration script that is
included in Proxy 2.0 or ISA Server (Array.dll?Get.Routing.Script or
Wpad.dat).
- You configure the default automatic configuration script to
use the range of IP addresses that you specify in either the Allow
clients to directly access IP addresses within this range setting in
ISA Server or the Do not use proxy for the following IP
Addresses setting in Proxy 2.0.
CAUSE When you add either one Internet Protocol (IP) address or a
range of IP addresses that are listed in ISA Server or Proxy 2.0 to the default
automatic configuration script that you want the browser clients to gain access
to directly, you allow browsers to bypass the Web proxy server for that
particular IP address range. In this scenario, the isInNet function is used.
The isInNet function queries a DNS server. When you either try to gain access
to a DNS name or type the DNS name in the Address box in the browser, the browser queries either its locally
configured DNS server or its locally configured WINS server to try to resolve
the DNS name to an IP address. If the browser is successful, it tries to match
the IP address that is returned by DNS or WINS with the IP addresses that are
used in the automatic configuration script. If these addresses match, the
browser gains access to that Web site directly. If these addresses do not
match, the request is sent to the Web proxy server as an ordinary Web proxy
request. However, if your organization does not allow browser client computers
to directly resolve DNS names on the Internet, when the browser client that
uses the IsInNet function initiates a local name resolution query, the query may
be unsuccessful.
The length of delay that occurs when the name
resolution query is unsuccessful depends on the name resolution mechanisms that
your organization uses. When the name resolution query is unsuccessful, the
browser skips the procedure in which the IP address that is retrieved by isInNet is matched. Instead, the browser sends an ordinary Web proxy
request, which causes the Web pages to load but with a long delay.
The delay occurs only when the name resolution query is unsuccessful. If the
clients are locally configured with a DNS server that can resolve all DNS names
on the Internet, you do not experience a delay when the Web pages load.
RESOLUTION To resolve this problem, use one of the following methods:
- Remove the IP addresses that are used in the automatic
configuration script. To verify that a list of IP addresses is used in the
automatic configuration script, review the client configuration settings in
either the ISA Server or Proxy 2.0 administration tool.
-or- - Make sure that all Web Proxy browser clients can resolve
all DNS names on the Internet by using its locally configured DNS
server.
STATUSMicrosoft
has confirmed that this is a problem in the Microsoft products that are listed
at the beginning of this article.
| Modification Type: | Major | Last Reviewed: | 1/17/2003 |
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| Keywords: | kbenv kbprb KB315810 |
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