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<TITLE>Netscape Handbook: Answers to Tough Questions</TITLE>
<A NAME="C0">
<B>
<FONT SIZE=+3>A</FONT><FONT SIZE=+2>nswers to tough questions</FONT>
</B></A>
<ol>
<A HREF="../index.htm">Netscape Handbook: Table of
Contents</A>
<li><a href="answers.htm#C1">Can you summarize the Options/Preferences menu items?</a>
<li><a href="answers.htm#C2">What does each part of an Internet address mean?</a>
<li><a href="answers.htm#C3">How do I install and configure helper applications?</a>
<li><a href="answers.htm#C4">What are the MIME types used by helper applications?</a>
<li><a href="answers.htm#C5">Can you summarize the Usenet newsgroup screens?</a>
<li><a href="answers.htm#C6">Why might I use Gopher?</a>
<li><a href="answers.htm#C7">Why might I use FTP (file transfer protocol)?</a>
<li><a href="answers.htm#C8">What is a cache and how does it work?</a>
<li><a href="answers.htm#C9">What is the difference between memory cache and disk cache?</a>
<li><a href="answers.htm#C10">What is the recommended size for each cache?</a>
<li><a href="answers.htm#C12">Where can I learn about Internet security?</a>
<li><a href="answers.htm#C13">Can I safely transmit personal information such as credit card numbers?</a>
<li><a href="answers.htm#C14">How does Netscape's security technology protect me?</a>
<li><a href="answers.htm#C15">To what degree can SSL security protect me?</a>
<li><a href="answers.htm#C16">How can I tell when security is in effect?</a>
<li><a href="answers.htm#C17">What does the Document Information dialog box tell me?</a>
<li><a href="answers.htm#C18">Are certificates required and where do you get one?</a>
<li><a href="answers.htm#C19">Can one certificate be used on multiple servers?</a>
<li><a href="answers.htm#C20">Do security features impose limitations on the ability to access sites?</a>
<li><a href="answers.htm#C21">How can I save files and images onto my hard disk?</a>
<li><a href="answers.htm#C22">What is dithering and how is it used?</a>
<li><a href="answers.htm#C23">How do you create hierarchical menus?</a>
<li><a href="answers.htm#C24">How do you convert hotlists to bookmarks?</a>
<li><a href="answers.htm#C27">Are there any Windows-specific tips or tricks?</a>
<li><a href="answers.htm#C38">What are Windows 95 Internet shortcuts?</a>
<li><a href="answers.htm#C29">What is the World Wide Web's place in the Internet?</a>
<li><a href="answers.htm#C30">How can I access the Internet?</a>
<li><a href="answers.htm#C31">What are SLIP and PPP?</a>
<li><a href="answers.htm#C32">What are TCP/IP and Winsocks?</a>
<li><a href="answers.htm#C33">What should I know about firewalls?</a>
<li><a href="answers.htm#C34">What are proxies and SOCKS?</a>
<li><a href="answers.htm#C35">How do server push and client pull work?</a>
<li><a href="answers.htm#C36">What are MIME, Types files, and Mailcap files?</a>
<li><a href="answers.htm#C37">How do I learn to write HTML and publish pages?</a>
</ol>
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C1">
<b>Can you summarize the Options/Preferences menu items?</b>
</A>
<P>
<DT><b>Window Styles</b>
<DD>Designate a home page and specify the style of toolbar buttons.
<P>
<DT><b>Link Styles</b>
<DD>Choose to underline links and specify the longevity of followed
links.
<P>
<DT><b>Fonts</b>
<DD>Select proportional and fixed fonts for a particular encoding.
<P>
<DT><b>Colors</b>
<DD>Select link colors and background pattern.
<P>
<DT><b>Mail</b>
<DD>Specify a mail server, user name, e-mail address, and signature
file for sending mail (and to establish a viable incoming mail
address so others can respond).
<P>
<DT><b>News</b>
<DD>Specify the host name for the news server (that supplies Usenet
newsgroups), a News RC directory, and display criteria.
<P>
<DT><b>Cache</b>
<DD>Specify the size and location of your disk cache and/or memory
cache.
<P>
<DT><b>Network</b>
<DD>Specify the size of a network buffer and the maximum number of
network connections.
<P>
<DT><b>Images</b>
<DD>Determine a priority for loading images and, depending on the
platform, the manner that colors are approximated.
<P>
<DT><b>Security</b>
<DD>Specify whether you receive notification dialog boxes regarding
the state of a document's security.
<P>
<DT><b>Directories</b>
<DD>Designate the temporary directory (before a helper application
launches a file, Netscape saves the file to disk in the temporary
directory).
<P>
<DT><b>Applications</b>
<DD>Specify the location of these supporting applications: Telnet,
HTML Source Viewer, and TN3270.
<P>
<b>Proxies</b>
<DD>Designate proxies and ports for FTP, HTTP, Gopher, News, WAIS
Security, and SOCKS host protocols.
<P>
<DT><b>Helper Applications</b>
<DD>Map MIME types and extensions of external applications and,
depending on the platform, actions to take.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C2">
<b>What does each part of an Internet address mean?</b>
</A>
<P>
The first part, <b>yourName</b>, identifies a user. The <b>@</b>
symbol (pronounced "at") separates the user name from the location of
the server computer. The last part, <b>aserver.bserver.org</b>,
identifies the location of the server computer. Addresses use
lowercase letters without any spaces.
<P>
The name of a location contains at least a string and, typically, a
three-letter suffix, set apart by a dot (the period symbol is
pronounced "dot"). The name of a location might require several
subparts to identify the server (a host name and zero or more
subdomains), each separated by dots . The three-letter suffix in the
location name helps identify the kind of organization operating the
server. (Some locations use a two-letter geographical suffix.) Here are
the common suffixes and organizational affiliation:
<ul>
<li><b>.com</b> (commercial)
<li><b>.edu</b> (educational)
<li><b>.gov</b> (government)
<li><b>.mil</b> (military)
<li><b>.net</b> (networking)
<li><b>.org</b> (noncommercial)
</ul>
E-mail addresses from outside the United States often use a two-letter
suffix designating a country. Examples are:
<ul>
<li><b>.jp</b> (Japan)
<li><b>.uk</b> (United Kingdom)
<li><b>.nl</b> (The Netherlands)
<li><b>.ca</b> (Canada)
</ul>
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C3">
<b>How do I install and configure helper applications?</b>
</A>
<P>
To install and configure
helper applications (many are already configured), use the <b>Helper
Applications</b> panel.
<P>
Helper applications expand Netscape's abilities. Netscape uses these
applications to let you automatically decompress downloaded
applications, listen to sounds, play movies, and get better display
of images. Most can be obtained free or as shareware.
<P>
Compression: You may find that programs are stored on the Internet in
formats that your computer doesn't understand. You may need to locate
a helper application program like PKUNZIP (Windows) to translate and decompress downloaded software
(and other helper applications).
<P>
Sounds: Most sound files aren't in a format that your computer can
automatically play. To listen to the different types of sound files
such as ULAW (common <b>.au</b> files), AIFF, and WAV, you'll need to
install a helper application that understands them.
<P>
Pictures and Movies: Netscape can display GIF, JPEG, and XBM files
internally, but you may prefer to use a dedicated image viewer. To
have Netscape automatically launch an external viewer, select the
<b>Mime Type</b> in the list, then choose the radio button <b>Launch
Application</b>. You'll need a player to view
<b>mpeg</b> movies.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C4">
<b>What are the MIME types used by helper applications?</b>
</A>
<P>
HTTP (HyperText Transfer Protocol) servers use HTML formatting.
Netscape software has the built-in capability to read HTML-formatted
pages (as well as the GIF, JPEG, and XBM graphic file formats).
Netscape can interpret many other file formats with the help of
external helper applications. To accommodate the file formats
requiring helper applications, Netscape keeps a mapping of file
formats to helper applications.
<P>
MIME (Multipurpose Internet Mail Extensions) is a standardized method
for organizing divergent file formats. The method organizes file
formats according to the file's MIME type. When Netscape software
retrieves a file from a server, the server provides the MIME type of
the file. Netscape uses the MIME type to establish whether the file
format can be read by the software's built-in capabilities or, if
not, whether a suitable helper application is available to read the
file.
<P>
For servers that do not provide a MIME type with a file, Netscape
interprets the file's extension (a suffix appended to a file name).
For example, the <b>.html</b> extension in the file name
<b>index.html</b> suggests a file in the HTML format. Likewise, a
<b>.zip</b> extension suggests a compressed file, an <b>.rtf</b>
extension suggests a file in the Rich Text Format, and so on. You can
view and configure the mapping of all MIME types to helper
applications by using the <b>Helper Applications</b> panel.
<P>
Technical note: The panel currently lacks a <b>Delete</b> button
and the ability to assign arbitrary values to file types. If needed,
advanced users might want to edit the preferences file directly.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C5">
<b>Can you summarize the Usenet newsgroup screens?</b>
</A>
<P>
Before you can use news for the first time you need to configure
Netscape to point to your Usenet news server. Set the host name of
your NNTP server in the <b>News</b> panel. Your newsgroup
subscription information is stored in a News RC file. If you have no
previous News RC file, Netscape creates one that lists a couple of
newsgroups designed for new users.
<P>
<DT><b>Subscribed newsgroups</b>
<DD>Shows a listing of all the Usenet groups that you have subscribed
to and lists the number of unread articles in each newsgroup. This
view also allows you to subscribe and unsubscribe to newsgroups.
<P>
<DT><b>Server list</b>
<DD>Shows a listing of the news servers you have connected to. This
view appears prior to the subscribed newsgroups view only if you have
connected to multiple news servers. Otherwise, this view is doesn't
appear.
<P>
<DT><b>Newsgroup listing</b>
<DD>Shows a list of all the unread articles in a
threaded format. The threaded format groups all articles that are
related to each other in a compact, ordered listing. Articles that
are responses to previous articles are nested under the parent
articles.
<P>
<DT><b>Article listing</b>
<DD>Shows a single article. The article listing
allows you to read the article, post a reply to the newsgroup, or
send a mail reply to the original poster. The article may contain
links to other articles or Internet pages.
<P>
<DT><b>Send Mail/Post News dialog</b>
<DD>Allows you to post a new article to a newsgroup, reply to an
existing news article, or send mail to an e-mail address.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C6">
<b>Why might I use Gopher?</b>
</A>
<P>
Some information on the Internet is offered through Gopher servers.
When you want information that happens to be on a Gopher server,
you'll click on a link whose URL begins with <b>gopher</b> (or enter
the URL in the location field).
<P>
Netscape lets you access Gopher servers in the same way you access
World Wide Web (<b>http</b>) pages. Though Gopher pages lack rich
formatting, menu listings allow you to bring content pages or
additional menu sublistings.
<P>
A menu is presented as a list of links, each link preceded by a small
icon indicating the type of resource the link brings. For example,
Gopher links can bring you:
<ul>
<li>menus
<li>text files
<li>images
<li>indexes
<li>movie and binary files
</ul>
Gopher indexes use form pages to allow you to find information on
Gopher servers. An index page typically provides an editable field
for you to enter a search string and a button for you to submit the
form to the Gopher server. The results of the search are a Gopher
menu listing items that match your search criteria.
<P>
Some files, such as short digital movies, require the use of
Netscape's helper applications. If available, Netscape automatically
launches the helper application required by a Gopher link.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C7">
<b>Why might I use FTP (file transfer protocol)?</b>
</A>
<P>
By clicking on a link whose URL begins with <b>ftp</b> (or by entering
the URL in the location field), you can navigate directories, view
files (including HTML and image files), and download software.
<P>
Netscape lets you access FTP servers in the same way you access World
Wide Web (HTTP) servers. However, you may find the FTP
directory and content pages have minimal formatting. When possible,
Netscape shows the type, size, date and a short description of each
file in a directory.
<P>
A directory is presented as a list of links, each link often preceded
by a small icon indicating another directory or a file. Clicking on a
directory link brings you a subdirectory. Typically, at the top of a
subdirectory is link that brings you the parent directory.
<P>
Clicking on a binary file or program automatically downloads the
software to a folder (designated in the <b>Directories</b> panel) on
your computer. After downloading, Netscape automatically looks for a
suitable helper applicationto launch the file. If the necessary
helper application is not available, Netscape presents you with a
dialog box asking whether you want to save or discard the downloaded
software.
<P>
Not all files are downloaded using FTP. By using the pop-up menu or by
clicking on a link with the shift key held down,
you produce the dialog box for saving an HTTP page, an
image file, or other file type to disk.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C8">
<b>What is a cache and how does it work?</b>
</A>
<P>
A cache temporarily stores the information on a page in your computer.
If you request a page that is stored in a cache, Netscape can
retrieve the page from the cache more quickly than retrieving the
page again from its location out on the network.
<P>
The first time you ask for a page, Netscape retrieves the page from
the network. No pages are permanently stored in a cache, but each
page you bring is temporarily stored in a cache. If you request a
page you have seen before, Netscape checks to see if the page is
available in a cache. For example, if you use the <b>Back</b> button
to bring a page, a cache can display the page more quickly than the
network can retransmit it.
<P>
Sometimes you may not want a page to be retrieved from a cache. The
page you brought initially may no longer be identical to the page
currently offered by the network. If a modification to a particular
URL has occurred, you may want the updated page rather than the copy
(now stale) stored in a cache. Remember, you have no control over
when a server updates its pages.
<P>
When you click on a link, choose a bookmark, enter a URL, or press the
<b>Reload</b> button, Netscape checks with the server to see if an
update has occurred before bringing a page from a cache. If any
change to the page has occurred, a fresh version is transmitted over
the network; otherwise, a copy is quickly retrieved from a cache.
<P>
When you press the <b>Back</b> button or choose a history item,
Netscape does no such check. Since you are explicitly requesting a
previously viewed page, Netscape tries first to retrieve the cached
copy (if still present in the cache) even if the server offers a more
recent version.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C9">
<b>What is the difference between memory cache and disk cache?</b>
</A>
<P>
Netscape supports two kinds of caches to improve performance and
reduce network traffic. When you bring a page from the network,
information is stored in both a memory cache and a disk cache.
Netscape retrieves a page from the memory cache more quickly than
from the disk cache, though retrieving from the disk cache is still
faster than fetching from the network.
<P>
The disk cache has the advantage of persistence. When you exit a
session (quit the Netscape application), the memory cache is emptied,
but the disk cache is maintained (and takes up space on your hard disk).
<P>
Sometimes a cache can get confused (such as when servers provide
inaccurate page modification dates). If you suspect a cache is acting
improperly (such as providing stale pages) or just wish to free up
space, you can clear the caches by pressing the <b>Clear Memory Cache
Now</b> and <b>Clear Disk Cache Now </b>buttons in the <b>Network</b>
panel.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C10">
<b>What is the recommended size for each cache?</b>
</A>
<P>
You can change the size of each cache to maximize its effectiveness. A
larger cache may increase Netscape performance, though allocating too
much space may constrict other applications. You might try to
increase the size of the memory cache to whatever your system
routinely has unused and increase the disk cache to between 2,000 and
5,000 kilobytes (2 and 5 megabytes).
<P>
You might find that a large disk cache increases the time required for
the Netscape application to quit. If Netscape's cache maintenance
causes undue delay when you exit the program, consider reducing size
of the disk cache.
<P>
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C12">
<b>Where can I learn about Internet security?</b>
</A>
<P>
The Internet security technology developed by Netscape Communications
to ensure private and authenticated communications (called SSL, short
for Secure Sockets Layer protocol) is an open platform put into the
public domain for the Internet community. Netscape Navigator and the
Netscape Commerce Server are the first products to offer this
nonproprietary technology.
<P>
The introductory information in the Netscape Navigator Handbook, accessed via
the <b>Help</b> menu, tells you why you need security on the Internet and
how to recognize the security features built into Netscape Navigator.
<P>
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C13">
<b>Can I safely transmit personal information such as credit card
numbers?</b>
</A>
<P>
You can enter your credit card number on a secure (<b>https</b>)
Netscape Navigator form and transmit the form over the Internet to a
secure Netscape Commerce Server without risk of an intermediary
obtaining your credit card information. The security features offered
by Netscape Communications technology protects commercial
transactions, as well as all other communications, from
misappropriation and fraud that could otherwise occur as information
passes through Internet computers.
<P>
Secure communications does not eliminate all of an Internet user's
concerns. For example, you must be willing to trust the server
administrator with your credit card number before you enter into a
commercial transaction. Security technology secures the routes of
Internet communication; security technology does not protect you from
unreputable or careless people with whom you might choose to do
business.
<P>
The situation is analogous to telling someone your credit card number
over the telephone. You may be secure in knowing that no one has
overheard your conversation (privacy) and that the person on the line
works for the company you wish to buy from (authentication), but you
must also be willing to trust the person and the company.
<P>
Server administrators must take additional precautions to prevent
security breeches. To protect your information, they must maintain
physical security of their server computers and control access to
software passwords and private keys.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C14">
<b>How does Netscape's security technology protect me?</b>
</A>
<P>
The security features built into Netscape Navigator and the Netscape
Commerce Server protect your Internet communications with:
<ul>
<li>Server authentication (thwarting impostors)
<li>Privacy using encryption (thwarting eavesdroppers)
<li>Data integrity (thwarting vandals)
</ul>
<P>
Without thorough security, information transmitted over the Internet
is susceptible to fraud and other misuse by intermediaries.
Information traveling between your computer and a server uses a
routing process that can extend over many computer systems. Any one
of these computer systems represents an intermediary with the
potential to access the flow of information between your computer and
a trusted server. You need security to make sure that intermediaries
cannot deceive you, eavesdrop on you, copy from you, or damage your
communications. The Internet does not provide built-in security.
<P>
The SSL protocol delivers server authentication, data encryption, and
message integrity. SSL is layered beneath application protocols such
as HTTP, SMTP, Telnet, FTP, Gopher, and NNTP, and layered above the
connection protocol TCP/IP. This strategy allows SSL to operate
independently of the Internet application protocols.
<P>
With SSL implemented on both the client and server, your Internet
communications are transmitted in encrypted form. Information you
send can be trusted to arrive privately and unaltered to the server
you specify (and no other).
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C15">
<b>To what degree can SSL security protect me?</b>
</A>
<P>
SSL uses authentication and encryption technology developed by RSA
Data Security Inc. For example, Netscape Navigator's export
implementation of SSL (U.S. government approved) uses a medium-grade,
40-bit key size for the RC4 stream encryption algorithm. The
encryption established between you and a server remains valid over
multiple connections, yet the effort expended to defeat the
encryption of one message cannot be leveraged to defeat the next
message.
<P>
A message encrypted with 40-bit RC4 takes on average 64 MIPS-years to
break (a 64-MIPS computer needs a year of dedicated processor time to
break the message's encryption). The high-grade, 128-bit U.S.
domestic version provides protection exponentially more vast. The
effort required to break any given exchange of information is a
formidable deterrent. Server authentication uses RSA public key
cryptography in conjunction with ISO X.509 digital certificates.
<P>
Netscape Navigator and Netscape Commerce Server deliver server
authentication using signed digital certificates issued by trusted
third parties known as certificate authorities. A digital certificate
verifies the connection between a server's public key and the
server's identification (just as a driver's license verifies the
connection between your photograph and your personal identification.
Cryptographic checks, using digital signatures, ensure that
information within a certificate can be trusted.
<P>
To evaluate the strategic and quantitative implications of the SSL
implementation of certification and public key technology, consult
the <b>SSL Protocol</b> specification via the <b>Help/On Security</b>
menu item.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C16">
<b>How can I tell when security is in effect?</b>
</A>
<P>
You can tell whether a document comes from a secure server by looking
at the location (URL) field. If the URL begins with <b>https://</b>
(instead of <b>http://</b>), the document comes from a secure server.
To connect to an HTTP server that provides security using the SSL
protocol, insert the letter "s" so that the URL begins with
<b>https://</b>. You need to use <b>https://</b> for HTTP URLs with
SSL and <b>http://</b> for HTTP URLs without SSL. A news URL that
starts with <b>snews:</b> (the letter "s" inserted in front of
<b>news:</b>) is used for a document coming from a secure news
server.
<P>
You can also verify the security of a document by examining the
security icon in the bottom-left corner of the Netscape Navigator
window and the colorbar across the top of the content area. The icon
consists of a doorkey on a blue background to show secure documents
and a broken doorkey on a gray background to show insecure documents.
The doorkey has two teeth for high-grade encryption, one tooth for
medium-grade. The colorbar across the top of the content area is blue
for secure and gray for insecure.
<P>
A mixed document containing secure and insecure information is
displayed as secure with insecure information replaced by a mixed
security icon. Some servers may permit you access documents
insecurely (using <b>http://</b>) to view mixed documents in full.
<P>
More detailed security information can be found by choosing the
<b>File/Document Information</b> menu item. Several configurable
notification dialog boxes inform you when you are entering or leaving
a secure space, viewing a secure document that contains insecure
information, and using an insecure submission process. You'll always
be warned if a secure URL is redirected to an insecure location, or
if you're submitting via a secure form using an insecure submission
process.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C17">
<b>What does the Document Information dialog box tell me?</b>
</A>
<P>
Choosing the <b>File/Document Information</b> menu item produces a
dialog box with a document's title, location (URL), date of last
modification, character set encoding, and the security status of a
document, Secure documents specify the type of encryption protecting
the document and the version, serial number, issuer, and server
subject of the certificate backing the document.
<P>
<DT><b>Encryption Key</b>
<DD>States the type of public key supported. For example, the
high-grade encryption key for U.S. domestic use only (RC4, 128-bit)
refers to the 128-bit key size for the RC4 stream encryption
algorithm.
<P>
<DT><b>Subject (server id)</b>
<DD>The certification request process requires that each server
administrator supply an e-mail address and certain identifying
information. Identifying information may include:
<ul>
<li>Country (C): two-character country code
<li>State or Province (ST): unabbreviated state/province name
<li>Organization (O): legal, registered organization name
<li>Organizational Unit (OU): optional department name
<li>Locality (L): city the organization resides or is registered in
<li>Common Name (CN): the server's fully qualified host name (such as:
hostname.netscape.com)
</ul>
<P>
<DT><b>Issuer (certifier id)</b>
<DD>Identifies the certificate authority responsible for issuing the
certification is identified. Identifying information is presented
using the same abbreviations as those used to identify the server (C,
for country, and so on).
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C18">
<b>Are certificates required and where do you get one?</b>
</A>
<P>
Currently, certificates are issued to organizations running servers
and are not issued to Netscape Navigator users. To operate using
security features, the Netscape Commerce Server requires a digitally
signed certificate. Without a certificate, the server can only
operate insecurely. If you are a server administrator and want to
obtain a signed certificate, you need to submit a certificate request
to a certificate authority, a third-party organization that issues
certificates, and pay an associated service fee.
<P>
Netscape Communications has engaged RSA Certificate Services, a
division of RSA Data Security, Inc., to issue certificates to
Netscape customers and will engage other certificate authorities over
time. The process to obtain a certificate is explained in the Netscape
Commerce Server manual. During the certificate request process, your
server software generates a public key/private key pair and you
choose a distinguished name. Online forms guide you through the
process of submitting the form to RSA.
<P>
RSA verifies the authenticity of each certificate request (making sure
requesters are who they claim to be). The approval process helps
protect you, your organization, and the certificate authority. Upon
approval, RSA digitally signs the request and returns the unique
digitally signed certificate to you through e-mail. You can then
install the signed, valid certificate and enable security. You'll
need to establish adequate precautions to maintain the integrity of
the signed certificate and your private key.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C19">
<b>Can one certificate be used on multiple servers?</b>
</A>
<P>
Technically, one certificate can be used on multiple servers, however
risks are involved that would discourage this choice in many
circumstances. If the same certificate is used on multiple servers,
any compromise of one server's public key and private key pair
endangers information on the other servers.
<P>
(Certificates are protected by public and private key pairs linked by
a powerful cryptographic algorithm. These keys have the ability to
encrypt and decrypt information. No one else's keys can decipher
messages to you encrypted with your public key. And no one else's
keys can be used to pose as you by sending messages encrypted with
your private key.)
<P>
Similar risks would be incurred if you were to choose to secure your
house, office, car, safety deposit box, and bike with the same key.
You would only have to carry around a single key, but you would not
have the flexibility to provide access to one item without providing
access to all items. If security was compromised for one item, it
would also be compromised for other items.
<P>
Multiple servers that are running on the same piece of hardware can
technically use the same certificate. However, as your software
installations expand, the need for different levels of security and
individual keys increases. The security requirements for information
served at remote locations or on separate hardware are best satisfied
by unique certificates.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C20">
<b>Do security features impose limitations on the ability to access
sites?</b>
</A>
<P>
The security protocol works as an adjunct to other protocols without
limiting access capabilities. You can use Netscape Navigator to bring
either secure or insecure documents. Nor does security limit
Netscape's Usenet news or electronic mail abilities.
<P>
If a document that is otherwise secure contains information that is
insecure, the insecure information is replaced by a mixed security
icon. However, a server may permit you to bypass this security
feature by accessing the mixed security document through the insecure
<b>http</b> protocol instead of the secure <b>https</b> protocol. The
security aspects of SSL protect you from insecure transmissions, but
do not limit your ability to receive insecure transmissions.
<P>
Online forms can be secure if the submit action is an <b>https://</b>
URL to a secure server. Netscape Navigator uses dialog boxes to
inform you about security status of the submission process when you
submit a form.
<P>
You can save a secure document (though secure documents are not cached
to disk among sessions). You can also view the HTML source of a
secure document. Security affects the transmission of a document
without affecting your ability to manipulate the document.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C21">
<b>How can I save files and images onto my hard disk?</b>
</A>
<P>
The <b>File/Save As</b> menu item produces a dialog box for saving a
page locally (onto your hard disk) in source or text format.
Source format produces a text file encoded with
the HTML necessary to reproduce the formatted text or image
faithfully; text format saves text without the HTML code. Whereas
some links, such as many FTP links, automatically download and save a
file to disk, <b>Save As</b> manually saves page files.
<P>
You can also save a page to disk without bringing the page to screen.
Position the mouse over a link or image, then click the right-side
mouse button to produce a pop-up
menu with the items <b>Save this Link as</b> and <b>Save this Image
as</b>. These menu items produce a dialog box for saving a file.
Clicking on any link with the shift key held down also produces a save dialog.
<P>
Saving a file onto your hard disk allows you to display the page's
information without any network connection. You can choose
<b>File/Open File</b> to display the HTML-formatted text or graphic
image of any local file saved in source format (though a page's
inline images may be replaced with icons). For GIF, JPEG, or other
nontext files to show up in the <b>Open File</b> dialog, you'll need
to select "All Files".
<P>
The pop-up menu item <b>View this Image</b> lets you see an isolated
image file. The pop-up menu item <b>Copy this Image Location</b>
copies the URL of the image file to the clipboard. Once you have the
URL, you can open the image and save the image onto your hard disk in
source format using <b>File/Save As</b> or the pop-up menu. You could
also use <b>View/View Source</b> to find the URL of an inline image
embedded in HTML code).
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C22">
<b>What is dithering and how is it used?</b>
</A>
<P>
Dithering is a software imaging process for arranging adjacent pixels
of varying shades into order to achieve a visual effect. The process
often enhances a computer's ability to display an image, particularly
useful when the color or resolution of the original image must
reproduced on computers with different display capabilities.
<P>
Netscape's display of inline GIF and JPEG sometimes needs to translate
an image's colors into similar colors available on your computer. If
your computer doesn't have color capabilities that match the color
information in an image, the image may look speckled.
<P>
On Windows, you can choose radio buttons in the <b>Images</b> panel to
<b>Dither to Color Cube</b> or <b>Use Closest Color in Color
Cube</b>. JPEG images, however, are always dithered.
<P>
When you choose to <b>Dither to Color Cube</b>, Netscape dithers the
computer's available colors to most closely match the image's colors.
When you choose <b>Use Closest Color in Color Cube</b>, Netscape
substitutes an available color that most closely matches the image's
colors. Images that are displayed with dithering take slightly more
time to display than images using color substitution.
<P>
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C23">
<b>How do you create hierarchical menus?</b>
</A>
<P>
On Windows:
<OL>
<li>Choose the <b>Bookmarks/View Bookmarks</b> menu item to view the
<b>Netscape Bookmarks</b> window.
<li>Click on the icon above the position you want a new folder. Each
folder represents a hierarchical menu header in a pull-down menu.
<li>Choose <b>Insert Header</b> from the <b>Items</b> menu, type a
title in the <b>Name</b> field, and click <b>OK</b> to create a new
folder.
<li>Drag and drop any bookmark icon on top of the new folder (or
select the folder and choose the <b>Insert Bookmark</b> menu item.
</OL>
<P>
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C24">
<b>How do you convert hotlists to bookmarks?</b>
</A>
<P>
Other browsers use hotlists similar to the way that Netscape uses
bookmarks. Users of other browsers may wish to preserve the URLs they
have accumulated as hotlists by converting them to bookmarks.
<P>
Choose the <b>Bookmarks/View Bookmarks</b> menu item. On Windows,
choose the <b>File/Import</b> menu item in the <b>Netscape
Bookmarks</b> window. These commands read any
HTML file containing links and convert the links into bookmarks.
<P>
To import a hotlist into Netscape, you should first convert your
hotlist to HTML. Several downloadable utilities perform this
conversion. You may also be able to use another browser's mail
command to transmit a hotlist in HTML format.
<P>
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C27">
<b>Are there any Windows-specific tips or tricks?</b>
</A>
<P>
<DT><b>Using Netscape without a network connection</b>
<DD>To use Netscape to browse local files without maintaining a
network connection, you should get the file <b>mozock.dll</b>. By
installing this file as <b>winsock.dll</b>, you can use the menu item
<b>File/Open File</b> to view local files on your hard disk (or use
the location field to type in a DOS pathname).
<P>
<DT><b>Registry versus netscape.ini</b>
<DD>The 32-bit version uses the system registry instead of a
netscape.ini file. To manually edit preferences, run regedit.exe. For
the 16-bit version: Netscape looks in <b>win.ini</b> in the section
<PRE> [Netscape]
ini=
</PRE>
for the location of the <b>netscape.ini</b> file (the INI file
contains initializations and preference settings used internally by
Netscape). If the file doesn't exist, Netscape looks for the file in
the directory where the application runs. Also: You may be able to
copy your INI file from other browsers to the <b>netscape.ini</b>
file. Be sure to add fields for History File and File Location, and
to convert hotlist entries to Netscape bookmarks.
<P>
<DT><b>Viewing HTML source documents</b>
<DD>To use Netscape (rather than an external viewer) as the HTML
source viewer, leave the <b>View Source</b> field blank in the
<b>Options/Preferences/Applications</b> panel.
<P>
<DT><b>Shortcut for cycling among open Netscape windows</b>
<DD>Press the <b>Crtl</b> and <b>Tab</b> keys together to consecutively
bring to the front each open Netscape window.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C38">
<b>What are Windows 95 Internet shortcuts?</b>
</A>
<P>
Internet shortcuts enable you to double-click on a desktop icon to
open Netscape with a particular page automatically loaded. The
desktop icon functions as a stand-alone bookmark, opening the
Netscape application (if necessary) and bringing to the screen the
page whose URL is stored as part of the shortcut. Internet shortcuts
are only available on the Windows 95 version of Netscape.
<P>
To create an Internet shortcut for any page, press the right mouse
button to display the pop-up menu and select the <b>Create
Shortcut</b> item. This displays the <b>Create Internet Shortcuts</b>
dialog box containing a <b>Description</b> field, a <b>URL</b> field,
and a check box.
<P>
By default, the <b>Description</b> field is preset with the words
<b>Shortcut to</b> followed by the title of the page you are viewing
and the <b>URL</b> field is preset with the the page's URL. You can
modify the contents of either field to specify any page you wish. If
the <b>Place on Desktop</b> check box is checked when you create the
Internet shortcut icon, the icon appears on the desktop; otherwise,
the icon appears in the Netscape folder. Click the <b>OK</b> button
to create the Internet shortcut.
<P>
You can also create an Internet shortcut for a particular page by
clicking on a link to the page, then dragging and dropping the link
onto the desktop.
<P>
Once you have created the Internet shortcut icon, you can drag and
drop the shortcut icon (like a bookmark) onto the Netscape window to
automatically open the shortcut page. Even if the Netscape
application is not running, you can drag and drop the shortcut icon
on top of the Netscape application icon to open Netscape and with the
shortcut page automatically loaded.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C29">
<b>What is the World Wide Web's place in the Internet? </b>
</A>
<P>
World Wide Web (WWW or Web) is one facet of the Internet consisting of
client and server computers handling multimedia documents. Client
computers use browser software (such as Netscape Navigator) to view
documents (pages). Server computers use server software (such as the
Netscape Commerce Server) to maintain documents for clients to
access.
<P>
Web documents are created by authors using a language called HTML
(HyperText Markup Language) that offers short codes (also called
tags) to designate graphical elements and links. Clicking on links
brings documents located on a server to a browser, irrespective of
the server's geographic location. Documents may contain text, images,
sounds, movies, or a combination.
<P>
Documents are addressed with a URL (Uniform Resource Locator or, for
short, location). Clients and servers use a document's URL to find
and distinguish among documents.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C30">
<b>How can I access the Internet? </b>
</A>
<P>
Some companies maintain a network that is linked to the Internet via
dedicated communication lines. Those with less substantial resources,
including most individuals, access the Internet via a service
provider. A service provider is a company that offers use of its
dedicated communication lines. If you have a modem, you can dial up a
service provider whose computers will connect you to the Internet,
typically for a fee. Dial-up access means that the modem on your
computer can log in to another computer that is hooked up to the
Internet.
<P>
The most popular dial-up access alternatives are shell accounts and
SLIP/PPP accounts. When using a shell account, you dial into a
service provider's computer and use the UNIX operating system to
indirectly connect to the Internet. With an indirect connection, your
computer does not interact with Internet computers. For example, if
you download a file from an Internet site, the file is saved on the
service provider's computer rather than on your computer. You then
have to transfer the file from the service provider's computer to
your home system. Shell accounts, while limited in features, have
historically been less expensive than direct access accounts.
<P>
When using a SLIP or PPP account, you dial into a service provider's
computer and run applications that directly connect to the Internet.
With a direct connection, your computer can use browsers with
user-friendly graphical interfaces to interact with Internet
computers. A direct connection lets you download files directly to
your system from remote sites. SLIP or PPP access to the Internet
offers more performance and convenience than a shell account.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C31">
<b>What are SLIP and PPP? </b>
</A>
<P>
SLIP, short for Serial Line Internet Protocol, and PPP, short for
Point-to-Point Protocol, are Internet standards for transmitting
Internet Protocol (IP) packets over serial lines (phone lines).
Internet information is packaged into IP packets, a method for
enclosing data into small, transmittable units (wrapped up on one
end, unbundled on the other).
<P>
A service provider may offer SLIP, PPP, or both. Your computer must
use connection software (usually provided by the service provider)
that matches the protocol of the server's connection software. PPP is
a more recent and robust protocol than SLIP.
<P>
<DT><b>CSLIP</b>
<DD>CSLIP, Compressed Serial Line Internet Protocol, is a
version of SLIP that supports compression.
<P>
<DT><b>Dynamic SLIP and Static SLIP</b>
<DD>When you use a SLIP or PPP
connection to the Internet, your service provider's server identifies
your computer by providing you with an IP address (a number like
192.34.32.81). Using dynamic SLIP, your computer is dynamically
allocated a temporary IP address (just for the immediate session)
from a set of IP addresses maintained by the server. Using static
SLIP, your computer is allocated a one-time, permanent IP address
(when your account is set up) for use in all your sessions. Static
SLIP means you have a static IP address.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C32">
<b>What are TCP/IP and Winsocks?</b>
</A>
<P>
<DT><b>TCP/IP</b>
<DD>TCP/IP, short for Transmission Control Protocol/Internet Protocol,
is the standard communications protocol required for Internet
computers. To communicate using TCP/IP, PCs need a set of software
components called a TCP/IP stack.
<P>
<DT><b>TCP/IP Stack</b>
<DD>Only the PC platform requires a TCP/IP stack. To make a successful
connection to the Internet, your PC needs application software such
as Netscape plus a TCP/IP stack consisting of TCP/IP software,
sockets software (Winsock.DLL), and hardware driver software (packet
drivers). Several popular TCP/IP stacks are available for Windows,
including shareware stacks.
<P>
<DT><b>Winsocks</b>
<DD>Winsock stands for Windows Sockets. Winsocks is a set of
specifications or standards for programmers creating TCP/IP
applications (communicating applications such as Netscape) for
Windows.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C33">
<b>What should I know about firewalls?</b>
</A>
<P>
A firewall protects one or more computers with Internet connections
from access by external computers connected to the Internet. A
firewall is a network configuration, usually created by hardware and
software, that forms a boundary between networked computers within
the firewall from those outside the firewall. The computers within
the firewall are a secure subnet with internal access capabilities
and shared resources not available to the computers on the outside.
<P>
Often, a single machine atop the firewall is allowed access to both
internal and external computers. Since the computer atop the firewall
is directly interacting with the Internet, strict security measures
against unwanted access from external computers are required.
<P>
A firewall is commonly used to protect information such as a network's
e-mail and data files within a physical building or organization
site. A firewall reduces the risk of intrusion by unauthorized people
from the Internet, however the same security measures may limit or
require special software for those inside the firewall who wish to
access information on the outside. A firewall can be configured using
proxies (and/or SOCKS) to designate access to information from each
side of the firewall.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C34">
<b>What are proxies and SOCKS?</b>
</A>
<P>
<DT><b>Proxy or proxy server</b>
<DD>A proxy allows access to the Internet from within a firewall. A
proxy is a special server that typically runs in conjunction with
firewall software. The proxy server waits for a request from inside
the firewall, forwards the request to the remote server outside the
firewall, reads the response, then sends the response back to the
client. Netscape lets you set the name and port number of proxy
servers in the <b>Options/Preferences/Proxies</b> panel in order to
resolve requests for access to Internet resources. Protocols such as
HTTP, FTP, Gopher, WAIS, and Security can have designated proxies.
Proxies may be preferred over SOCKS for their ability to perform
caching, high-level logging, and access control.
<P>
<DT><b>SOCKS</b>
<DD>SOCKS is software that allows computers inside a firewall to gain
access to the Internet. SOCKS is usually installed on a server
positioned either inside or on the firewall. Computers within the
firewall access the SOCKS server as clients to reach the Internet.
Netscape lets you set the name and port number of the SOCKS host
(server) in the <b>Proxies</b> panel. On Windows, the host is
specified in the registry (32-bit) or INI file (16-bit).
<P>
Sometimes you need to restart Netscape after changing the SOCKS host.
Netscape supports version 4 of SOCKS defined by the socks.cstc.4.1
implementation.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C35">
<b>How do server push and client pull work?</b>
</A>
<P>
Generally, pages are brought to your screen as a result of your input.
You click on a link or an image to request a page. But servers also
have the ability to deliver an updated version of a page to your
screen automatically. For example, a weather watcher might want to
see an updated satellite photo at 15-minute intervals. Netscape
provides the pages creators and server administrators two
complementary tools for making this work.
<P>
<DT><b>Server push</b>
<DD>the server transmits page information to your screen. The Netscape
applications displays the information and leaves the connection to
the server open. With an open connection, the server can continue to
push updated pages for your screen to display on an ongoing basis.
You can close the connection by closing the page.
<P>
<DT><b>Client pull</b>
<DD>the server transmits page information to your screen along with
programming code that automatically instructs the Netscape
application to perform an action such as "reload this page in ten
minutes" or "go load this URL in two minutes". After the specified
amount of time has elapsed, the client (the Netscape application on
your computer) pulls updated pages to your screen according to the
instructions it has been provided along with the page. You can
terminate the page's actions by closing the page.
<P>
In server push, a HTTP connection is held open for an indefinite
period of time (until the server is finished sending data to the
client or until the client interrupts the connection). In client
pull, a HTTP connection is never held open; rather, the client is
told when to open a new connection and what data to fetch. Server
push uses a variant of the MIME message format "multipart/mixed" that
lets a single message (or HTTP response) contain many data items.
Client pull uses an HTTP response header (or equivalent HTML tag)
that tells the client what to do after a specified time delay.
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C36">
<b>What are MIME, Types files, and Mailcap files?</b>
</A>
<P>
MIME is short for the Multipurpose Internet Mail Extensions protocol.
This protocol is used in Internet communications to transmit
documents of varying formats. The protocol handles complexities by
establishing a relationship (a mapping) between the format of a
document's content and the format of the document's computer
representation. Applications using MIME can establish the type of
software necessary to interpret the content of a transmitted
document. With the proper Helper Application settings and software,
Netscape can automatically initiate the necessary actions to provide
you access to content transmitted in numerous formats.
<P>
On Windows, the mapping of MIME types is handled in the
<b>Helper Applications</b> panel.
<P>
As an example, an audio file <b>mySound.au</b> plays using the
<b>audiotool</b> application.
<P>
<HR ALIGN="right"WIDTH=85%>
<P>
<A NAME="C37">
<b>How do I learn to write HTML and publish pages?</b>
</A>
<P>
You can write HTML (HyperText Markup Language) pages using any word
processor or text editor. (To publish pages on the Internet, you need
to submit your pages to a server computer using server software.)
HTML uses embedded codes (tags) to designate graphical elements and
links. These codes can be produced simply from your keyboard using
angled brackets and the slash character. For example, the tag
<b><B></b> presents text in bold letters. An HTML source file
containing the expression <b><B>This stands out.</B></b>
is displayed on screen in bold. Notice that the tag <b></B></b>
is required to notate the end of the bold expression.
<P>
HTML consists of many such tags, including tags for big headlines,
underlining, italics, titles, and paragraph breaks. Netscape
also supports tags that allow you to create tables and custom
backgrounds. Consult Netscape's online pages to learn how to take
advantage of these features.
<P>
One feature you'll certainly want to use is the HTML link. Here's
example HTML that creates a link for users to click on:
<P>
<PRE> <A HREF="http://www.worldnet.att.net/">Home</A>
</PRE>
<P>
The part of the tag between quotation marks is the URL of the page
that clicking on the link brings. The text following the URL contains
the highlighted text (Home) the user sees on screen. The tag coding
and brackets are also a required part of the link. The method to
insert images in your pages in very similar to that of inserting
links. Inline images are links to image files. To see any one page's
HTML source, you can choose the <b>View/Source</b> menu item. This
command displays the text and tags used to create the content and
content style of the current page.
<P>
<A HREF="../index.htm">Netscape Handbook: Table of
Contents</A>
<HR SIZE=4>
<A HREF="mailto:info@netscape.com"><I>info@netscape.com</I></A><BR>
Copyright © 1994, 1995 Netscape Communications Corporation.
<P>