Your question requires some more detail. Are you asking about security  from
a configuration and planning point of view? (That is, prior to installing
SharePoint on a server.) Or are you asking about security post installation
because you have issues getting the browser  to view your Web site?

I would say the answer to your question is 'it depends': it depends on the
security requirements of your organization, the context in which you will be
using SharePoint. sharepoint  is designed to work in a Windows NT/2000
environment, and you can employ IIS to manage security settings. You can
also establish security by virtue of assigning users and groups (NT/Windows
2000 users/groups) to SharePoint roles, and you can establish these security
settings at the level of documents, folders, and so on.

So yes, there are specific  security settings  and the administrator has to be
the one to set them for each deployment depending on user and organizational
requirements.

I would recommend you purchase the Microsoft SharePoint Portal server  2000
Resource Kit, and possibly also the Windows 2000 Server Resource Kit and
read the chapters on security for more details.

I just wanted to know if the settings  of the browsers or the IIS
effect the role security  of the sharepoint  or not.

I asked the question because I'm facing the following problem:

All the users in our SPS have the authority of author so they should
all be able to publish documents while most of them now cant do such
things.I did an experiment. I loged in with a user name who can't
publish a document from another user's machine who can publish and
vice verse and the results were positive

(thats why i asked the question)

a.mutalib

Under IIS, right click on your Web site and select Properties, then click on
the Directory Security tab. Click on the Edit button and check to see what
authentications methods you have enabled. I have integrated Windows
authentication checked on my implementation. That way, when I assign users
to roles (like author), I do so with their Windows identity (or a group to
which individuals belong) and only those in that group can access the Web
site. Have you looked at that?

It's already done..................