The following procedure, developed for the UNIX operating system, should provide you with the current version of this document:

An online version should be available at http://www.ntp.org/ntpfaq/. The current top-level file is NTP-a-faq.htm.

Please note that checking out the CVS sources will provide the SGML sources as well as the HTML pages. I cannot make a statement about what will be available via HTTP, but I expect that only the HTML files are there, and listing the directory will not work.

I edit this document in my spare time. My spare time is quite rare. Therefore I rely on contributions to improve this work (see Q: 1.4.2.). Feel free to contact me if you want to make a contribution.

I hope to update this document as soon as important new stuff is available. The same applies for severe bug fixes.

This document tries to answer frequently asked questions (FAQs) that can not (at least virtually) be answered easily from the standard documentation.

In addition to just answering questions that users had, this document also tries to give a gentle introduction and guidelines to the newcomer. The authors believe that it's better to use NTP correctly right from the start rather than fixing all the problems after they occur.

Gentle in the paragraph above means not too technical and not too theoretical. However some basic, non-trivial understanding of real-life is required at several points, so please accept these deviations from the goal.

Unless it simply has not been written yet, there may be other reasons:

1. The editors don't want to copy documentation that is publicly available already. This is especially true for standards, specifications and manuals. The editors think that referring is better than copying. The intention is to avoid redundancy while saving labour at the same time.

2. Either the problem or the solution is too vague to document it. This is true for very special configurations that are not at all common. After all, we want to answer frequently asked questions here.

The answer to this question is quite delicate! The guidelines are probably these:

• Try to understand the existing structure of the document.

• If there are similar entries there already, see where the new one fits best. Usually it's right near the existing one, or in a corresponding section. Possibly it makes sense to create a new section or division.

In the good old times the Internet was a valuable source of information, and people were happy to share their knowledge. These days, however, people think of E-Commerce, how to make money.

I started writing this FAQ not to make money, but to have a reference to refer to. Thus I hope I'll be able to provide the needed information to more people more quickly. Unfortunately I do not know everything. So if you have solved some problem that may be of interest to other people as well, please share your experience.

Contributions are very much appreciated. Depending on your possibilities you can:

1. Tell me about some error or incomplete information given. I call it a minor contribution. If you want to be listed in the hall of fame (also called credits), just tell me when contributing. If you prefer anonymous contributions, they are welcome just the same.

2. You can suggest an addition consisting of a question together with its answer. I call this a major contribution. Major contributions are definitely worth being listed as author in the header of the document if you like. Of course you can downgrade your contribution to plain credits or nothing if you prefer.

   Contributions are accepted in any format, but I prefer plain US-ASCII or ISO-8859-1. If you can avoid it, don't send files in some text processing format.

3. Supplying a valid patch against the source of this document will make the most appreciated contribution. This allows you to be listed as co-author. As before, you can downgrade your contribution as you like. For details see In what format should I send contributions?.

This document is most likely not written in the format you are seeing. The document source is written in SGML (Structure Generalized Markup Language, ISO-8879) using the DocBook DTD (Document Type Definition). Therefore the source document has a rather fixed structure, much unlike HTML. See also Q: 1.4.6..

So the essence is: Try to learn writing documents conforming to the DocBook DTD. In the meantime I'll do my best converting your input to the proper format (See the more general discussion in How can I contribute?).

The sources controlled by CVS can be updated by various people, but contributions should be sent to the currently defined editor. Every HTML file contains a mailto: hyperlink to the editor. Many browsers allow sending comments to the author that way. Another method is to visit the file ChangeLog found where the sources are (See Q: 1.1.1.).

Probably the fault of the editor. Maybe he thought you don't want to be listed, or he simply forgot. Section 1.1 shows the names the editor was aware of.

Well, I'm not getting paid for my work, so I tried to learn something new while writing this piece of documentation. SGML is one of the dinosaurs of information technology, an endangered species that may be killed by the more agile XML. So maybe feeding dinosaurs is just cool.

DocBook is just another monster that is used by even larger monsters like HP for documentation. Definitely it's also animal, because it's used by O'Reilly & Associates, Inc.[1] Finally it's an open technology: All specifications (and many tools) are freely available.

Specific output formats are generated by applying style sheets within a framework consisting of James Clark's JADE (James' DSSSL Engine) and Norman Walsh's Modular DocBook Stylesheets. While this document probably will be used mostly in HTML format, other formats like TeX and RTF (Rich Text Format) can be generated as well.

I'm editing this document with the Linux/GNU operating system. Most Linux distributions come with the required tools. In my distribution these tools are in the following packages:

So if you want to edit and validate any changes you are making, try to get the equivalent tools for your operating system as well. If you like the pain, you can use these tools on Microsoft Windows™ as well.

Basically the command to generate HTML files is jade -t sgml -d NTP-FAQ.dsl#html NTP-FAQ.sgml where the environment contains these special settings:

SGML_CATALOG_FILES=SGML_CATALOG_FILES=/var/lib/sgml/CATALOG.docbk41
SGML_SEARCH_PATH=/usr/share/sgml/docbook/dsssl-stylesheets/html

You are lucky: Actually the source of the FAQ uses no formatting rules at all, even the DSSSL code relies on HTML classes and style sheets to do the rendering. All properties like borders, colours, and font attributes are taken from a cascading style sheet (CSS).

In practice, this means you don't have to change the HTML source to change the appearance. Instead simply provide your favourite user style sheet to do the formatting. If you prefer no fancy attributes at all, just empty the docbook.css file.[2]

If the output looks extraordinarily odd, you may have a broken HTML browser. See also Q: 1.5.2..

If you think colours are inconsistently chosen, please make a suggestion for future improvement. If you dislike single colours or combinations thereof, please suggest a change. Doing that job is more an art than a science.

I'm aware that some elements are not rendered the best possibly way. As I don't waste much time (at least not even more time) with rendering of elements, I strongly rely on Norman Walsh's competence in JADE programming. I'm hoping that things will improve over time.

*.ACRONYM { color: #5838d0 }

If your browser goes mad, and your vendor allows you to report bugs, feel free to report the problems to them. If you think I went mad, feel free to tell me too ;-)

This FAQ is intended to be read with the famous "any browser". It means that standard HTML is used, omitting any fancy extensions. Still individual browsers may implement different subsets of the standard.

I usually test the output using the following browsers in Linux (roughly ordered by fanciness):

The popular GIF format supported by many browsers relies on a compression algorithm that is patented, and the owner of the patent wants to receive money from everyone making GIF files. PNG (Portable Network Graphics) uses a different algorithm for compression and does not require payment.

Netscape Navigator (e.g. version 4.74) seems to have a bug with relative font scaling. Try to disable using stylesheets, or try a recent Mozilla. See also Q: 1.5.1..

Sorry, I have my daily frustration with frames, so I don't want any more. Despite of that I think that most frames just consume valuable space on either your screen or on your print-out.

Currently scripting is neither fast nor portable, so I don't use it.