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Browsers |
Caching |
Connectivity |
Graphics |
HTML |
HTTP
Q. Why are some Macintosh clients with AOL 3.0 having connection problems?
A. There is a known problem in the AOL 3.0 client for the Macintosh that affects some
transactions on secured web sites, causing the connection to hang. AOL 4.0 resolves this problem; the
following section addresses the solution for current AOL 3.0 Macintosh clients who have not yet upgraded
to AOL 4.0.
Path MTU Discovery is a TCP protocol used to determine the largest unfragmented packet size than
can go through the network. When the client software performs Path MTU Discovery, you can set the
DF (don't fragment) bit, which causes a packet to be dropped if it is too large. If the packet is dropped,
you receive an Internet Control Message Protocol (ICMP) message that alerts you to reduce future packet
sizes and retransmit the last packet. For security reasons, many secured web sites block ICMP messages. If
you decide to block ICMP messages, use one of the following ways to stop the connection from hanging:
Disable Path MTU Discovery on the last router before your firewall to allow the client to
receive an ICMP message.
-or-
Allow ICMP messages to go outbound, but block the ICMP packets inbound through your routers.
Q. What browsers and client software are currently in use?
A. All the current AOL clients that have an integrated browser are listed in the
AOL Browser Features and Functionality Table.
Q. Why does AOL use a proxy cache? No one else does!
A. Actually, many companies and service providers use proxy systems. Proxy servers
are often used to enforce security or content restrictions, similar to our
Parental Control feature. Caches are used to reduce network bandwidth and
improve performance. If AOL did not use cache technology, a large part of
the Internet backbone would need to double or triple in size.
Q. Does AOL cache cookies?
A. A cookie is just
another HTTP header line. It plays no role in the decision to cache a document. If the document
does not contain the appropriate Expires header, the document and the
cookie header may be cached. In most cases, it is an error for a web site
to use cookie header lines without also using an Expires header. The
future HTTP
1.1 protocol adds additional header control lines that may make cookie
cache management easier to implement.
Q. Does the AOL proxy server support HTTP 1.1?
A.Yes, because this is now a finalized industry standard.P>
Q. Does the AOL proxy server support the META tag?
A. No. The META tag is an HTML tag that instructs a web site server and/or a
client browser to take some action. Because the AOL proxy server does not
read the HTML content portion of a document, the AOL proxy server does not
take any action.
Q. Can a META tag be used to set the Expires header?
A. Only if the web server hosting the document translates the META tags into real headers. Caching
servers cannot read HTML code to find META tags - only headers.
Q. What is the syntax of the Expires header and how do I set it?
A. Please see Caching
Q. I am still getting old pages and I am certain that the site has been updated,
how do I clear my BROWSER CACHE?
A.
Even though AOL's Proxy cache is updated every 24 hours, a member can clear
their Browser Cache and force the reload of a page. This is done by either
reducing the browser History to "0" and manually clearing all pages in
history by deleting the files in the temporaty internet files tolder located in the Windows Directory or PC users can force a refresh by holding down the CONTROL key on their keyboard and mouse clicking on the AOL browser reload icon. The latter will completely
clear all items in history.
Q. Can I use the IP
address of the request to track a member's access to my site?
A. No. Because AOL uses proxy servers to service the requests made by members, webmasters see the IP address of the
gr server, not the DAHA
of the member in their web site log files. The problem with trying to use
the IP address to track access is that there may easily be multiple members
assigned to a proxy server. All of the member requests would appear to be
coming from one member if you assumed a relationship between member and IP
address. In addition, members may be reassigned to a different proxy server
during a session. See also Network Info.
Q. Does the AOL cache support multiple views of my web site?
A. Yes. The proxy software caches HTML based on the browser's User-Agent strings. For example, you can
have static documents representing Windows vs. Mac or English vs. French content. Each version of
the document is cached separately and served to the member as appropriate.
Q. Does AOL log all web activity?
A. Yes, our proxy servers maintain a log of activity. We use these logs to track
security issues, monitor service performance, and generate activity reports.
However, we do not track and report on the specific activity of a member.
Q. How do I get my site approved for kid and teen access?
A. Send e-mail to Microsystems Cyber Patrol or go to Keyword:
Parental Controls.
Q. Our IP address was just changed and our AOL visitors are experiencing a DNS error. When does AOL update
it's DNS to see new IP's?
A. AOL's DNS servers respect TTL (the Time To Live). Check with your previous Internet service provider as
to the setting value of the old TTL. When that value expires, AOL's DNS will then propagate the new IP address.
Q. Why do some of my images look slightly blurry in AOL's Browser?
A. America Online utilizes graphics compression software that speeds up the delivery
of web pages to it's members by compressing images and various multimedia
applications. Images that are BMP, GIF or JPG are converted into the proprietary
Johnson-Grace image format .ART. All AOL members have the option of deselecting
"Used Compressed Graphics" in their Web Preferences.
Q.I have deselected "Use Compressed Graphics" in my WWW preferences and the images still look the same. What am I doing wrong?
A.This is a Caching issue.
In your WWW preferences you can set your history to "0" pages and clear the History. You must also delete the files
in your Temporary Internet Files folder.
Holding down the "Control" key on your keyboard and simultaneously mouse-clicking on the Browser Reload icon while
the browser window is active will also clear your cache and display the latest data from the website.
Q. How do I use the Expires attribute within the META tag?
A. The META tag has three attributes. IMPORTANT: Implementation of this example may not prevent your page from being cached. Your server must be configured to interpret the META tag and include the appropriate headers in it's
response. See EXPIRES header.
- NAME, used to name a property such as author, publication date, etc. If absent,
the name can be assumed to be the same as the value of HTTP-EQUIV.
- CONTENT, used to supply a value for a named property.
- HTTP-EQUIV, used to bind the element to an HTTP response header. If the syntax of the
HTTP response header named by this attribute is known, then the contents can be processed based on a well-defined
syntactic mapping, whether or not the DTD includes anything about it. HTTP header names are not case sensitive.
If the header name is absent, use the NAME attribute to identify this META information. It
should not be used within an HTTP response header. The Expires attribute can be defined within the HTTP-EQUIV as
shown in the example below.
For example, if the document contains:
The server includes the following response headers:
Expires: Tue, 04 Dec 1993 21:29:02 GMT
Keywords: Nanotechnology, Biochemistry
Reply-to: dsr@w3.org (Dave Raggett)
When the HTTP-EQUIV attribute is absent, the server does not generate an HTTP response header for this META information.
For example:
Do not use the META tag to define information that should be associated with an existing HTML element. For example,
an appropriate use of the META tag is:
Do not give an HTTP-EQUIV attribute the same name as a response header that is typically generated only by the HTTP
server. Some inappropriate names are Server, Date, and Last-Modified. Whether a name is inappropriate depends on the
particular server implementation. It is recommended that servers ignore any META tags that specify HTTP equivalents
(non-case-sensitive) to their own reserved response headers.
Q. How do I know what my server is saying to the browser?
A. Access HTTP Headers to view response information.
To access HTTP Header Information:
From the UNIX command line, type:
telnet www.xxx.xxx 80
Something similar to the following appears:
Trying xxx.xxx.xxx.xxx
Connected to www.xxx.xxx
Escape Character is '^]'
Type:
HEAD / HTTP/1.0
Press twice. Something similar to the following appears:
HTTP/1.0 200 OK
Date: month, date time
Server: server type
Refresh: 0; URL = http://xxx.xxx.xxx/xxx.xxx
Content-Length: some number
Content-Type: text/html
This information indicates that the server is understanding the request at the most basic level.
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