There can be various reasons for a slow browsing problem, and we'll try to figure it out step-by-step.
The steps are given as follows:
- First, check that you don't simply have a loaded line to the Internet or core connections in the network, high error rate on the communications line, or any of these obvious issues that cause most of the problems (see Chapter 5, Using Basic Statistics Tools chapter and Chapter 6, Using Advanced Statistics Tools for further details).
- To negate a TCP issue (as explained in detail in Chapter 11, Transport Layer Protocol Analysis), check the following details:
- In the expert info window, you don't get too many retransmissions and duplicate ACKs (< 1% is still tolerable).
- Make sure that you don't get resets on the HTTP connections. It might be due to firewalls or site restrictions.
- Make sure that you don't get the following DNS problems:
- Slow response time
- Names are not found, not correct, and so on
- If none of these apply, well! Let's dig in to HTTP.
When you open a web page for the first time, it can take a few seconds. In this case, you should check the following conditions:
- Check whether the line is not loaded.
- Check the delay on the line (a ping to the website will do the job).
- Look for error codes. Usually you will see the reason for the error on the browser, but not always.
- Configure the filter http.response >= 400 and see how many errors you get. In the following sections, we see several examples of what you should pay attention to.
|
Code |
Status |
Explanation |
|
100 |
Continue |
Request completed successfully and the session can continue. |
|
101 |
Switching protocols |
The server is changing to a different HTTP version. It will be followed by an upgrade header. |
|
Code |
Status |
Explanation |
|
200 |
OK |
Standard OK response |
|
201 |
Created |
The request has been fulfilled and a new resource has been created |
|
202 |
Accepted |
The request was accepted and is still in process |
|
203 |
Non-authoritative information |
The request was received with content from another server, and it was understood |
|
204 |
No content |
The request was received and understood, and the answer that is sent back has no content |
|
205 |
Reset content |
This is a server request to the client to reset the data that was sent to it |
|
206 |
Partial content |
Response for a partial document request |
|
Code |
Status |
Explanation |
What to do |
|
300 |
Multiple choices |
The requested address refers to more than one file. It can happen, for example, when the resource has been removed, and the response provides a list of potential locations for it. |
- |
|
301 |
Moved permanently |
The requested resource has been moved permanently. Future requests should be forwarded to the attached URI. |
- |
|
302 |
Moved temporarily (found) |
Page has been moved temporarily, and the new URL is available. Usually, you will be automatically forwarded. |
Usually, you will see a found code, and then another GET to the URL indicated |
|
303 |
See other |
The response to the request can be found in a different URI. It should be retrieved using an HTTP GET to that resource. |
- |
|
304 |
Not modified |
When a request header includes an if modified since parameter, this code will be returned if the file has not changed since that date. |
- |
|
305 |
Use proxy |
The requested resource must be accessed through a proxy. |
Check what proxy is required |
|
Code |
Status |
Explanation |
What to do |
|
400 |
Bad request |
The request could not be understood by the server due to a syntax problem. The request should be modified by the client before resending to it. |
Check the website address. This can also happen due to a site error. |
|
401 |
Authorization required |
The client is denied access due to the lack of authentication codes. |
Check your username and password. |
|
402 |
Payment required |
Reserved for future use. |
|
|
403 |
Forbidden |
The client is not allowed to see a specific file. This can be due to the server access limit. |
Check the credentials. Also, there are fewer chances that the server is loaded. |
|
404 |
Not found |
The requested resource could not be found. |
This can be because the resource was deleted, or it never existed. It can also be due to URL misspellings. |
|
405 |
Method not allowed |
The method you are using to access the file is not supported or not allowed by the resource. |
|
|
406 |
Not acceptable |
Content generated by the resource is not acceptable according to the client request. |
Check/update your browser. |
|
407 |
Proxy authentication required |
Request authentication is required before it can be performed. |
The client must first authenticate itself with the proxy. |
|
408 |
Request timed out |
It took the server longer than the allowed time to process the request. |
Check the response time and load on the network. |
|
409 |
Conflict |
The request submitted by the client cannot be completed because it conflicts with some established rules. |
Can be because you try to upload a file that is older that the existing one or problems alike. Check what the client is trying to do. |
|
410 |
Gone |
The URL requested by the client is no longer available from that system. |
Usually, this is a server problem. It can be due to a file that was deleted or location was forwarded to a new location. |
|
411 |
Content length required |
The request is missing its content length header. |
Compatibility issue on a website. Change/update your browser. |
|
412 |
Precondition failed |
The client has not set up a configuration that is required for the file to be delivered. |
Compatibility issue on a website. Change/update your browser. |
|
413 |
Request entity too long |
The requested file was too big to process. |
Server limitation. |
|
414 |
Request URI too long |
The address you entered was overly long for the server. |
Server limitation. |
|
415 |
Unsupported media type |
The file type of the request is not supported. |
Server limitation. |
A simple example for a client error is presented in following screenshot. To get to this window, perform the following steps:
- Right-click on the packet with the error code.
- Choose Follow TCP stream. You should get the following window:
You can see the following conditions:
- I tried to browse the URI /poker-client/broadcast.htm(marked as 1 and 3 in the preceding screenshot)
- The URI was forwarded by the referrer: http://www.888poker.com/poker-client/promotions.htm (marked as 2 in the preceding screenshot)
- The status code was 404 Not Found (marked as 4 in the preceding screenshot)
Just to clear things, I was not playing poker. I was working on a networking problem.
|
Code |
Status |
Explanation |
What to do |
|
500 |
Internal server error |
The web server encountered an unexpected condition that prevented it from carrying out the client request for access to the requested URL. |
Response that is usually caused by a problem in your Perl code when a CGI program is run. |
|
501 |
Not implemented |
The request cannot be executed by the server. |
A server problem. |
|
502 |
Bad gateway |
The server you're trying to reach is sending back errors. |
A server problem. |
|
503 |
Service unavailable |
The service or file that is being requested is not currently available. |
A server problem. |
|
504 |
Gateway timeout |
The gateway has timed out. This message is like the 408 timeout error, but this one occurs at the gateway of the server. |
Server is down or non-responsive. |
|
505 |
HTTP version not supported |
The HTTP protocol version that you want to use for communicating with the server is not supported by it. |
Server does not support the HTTP version. |
You can get the service unavailable status (code 503) due to various reasons. In the following example, there is a small office that has the following complaint: they can browse Facebook, but the moment they click on a link on this site, they get the new page as blocked. In the following screenshot, you can see that the problem was simply a firewall that blocked it (obviously):
