DNS: The Bind Leading the Bind
Hiding beneath the surface of your web browser, email and instant messaging lies a phone book for computers on the Internet. We call it Domain Name System or DNS. It looks up the names of other computers and calls them to chat, shake hands or whatever PCs do with their own kind.
Aside from hiding beneath hundreds of millions of people's awareness, some people know that DNS seems to like Linux. In fact, they're sort of made for each other. You can get Linux for free and the software for DNS comes packaged with Linux distributions and it's also free.
Almost universally DNS servers run Berkeley Internet Name Domain or BIND. Any one wanting their own web site and/or domain needs two domain servers. That's just one of the rules of the game. Obviously, the requirement for two servers made Linux the choice of ISPs and system administrators because it saves people money.
If you want to work as a Linux sysadmin and travel that career path, then you'll need to learn DNS. That's where the other shoe drops. Keep reading.
The big directory runs in a distributed mode and it wants the owner of a domain to provide it's own directory listings. Basically, you have to write your part of the DNS system because the rest of the Internet depends on you doing that.
A slight catch exists. The Internet Engineering Task Force (IETF) established our current DNS protocols long before the enormous growth of the Internet. No one really knew if it would scale.
Funny as it may seem, DNS worked even under the tremendous stress placed on it as the Internet grew exponentially. The Domain Name System simply grew as the Internet grew. And while the current system remains a bit archaic, it works and it works well.
It just requires a set of skills popular well over two decades ago. The standards of DNS did not have a chance to adjust their technical underpinnings while the great Internet adoption took place. The protocols came into existence in 1985. Oh, did I mention that those protocols lack something we call intuitive.
Do I Have To?
Simple answer: yes. Linux system administrators have to learn DNS. Even if you off-load your DNS to a service provider, you'll likely wind up getting all or part of it back. The Internet continues to change and the demands requiring the resolution of friendly names like domain.org to an IP address has become mission critical.
Let's look at the reality in the market. Businesses, especially big ones, hate to change their systems. Forget the noise people make about migrating or upgrading this or that. Big orgs hate it.
But, Big orgs also have to keep current or they'll get bloodied by nimbler businesses using new standards and protocols. Just so those angry Big orgs can keep their legacy applications in use by let's say 100,000 employees on terminals or PCs, a new industry emerged. We call it the web-enablement segment.
Along comes application servers like JBoss and WebSphere and suddenly disparate silos of servers start speaking to each other. Then we have front-end applications speaking to their supply chain while customers and vendors come into the enterprise.
The rest of the world doesn't even know that another layer of applications surrounds those legacy apps and data repositories. It reminds me of the convergence of public libraries. One on side of the Ethernet lies the library's old database. On the other side lies a LAMP application talking to other servers as if they all had the same MySQL database engines full of book titles, authors and subjects.
How does all this work? Oh, it works because a twenty year old directory with a billion entries almost instantly looks up a name, translates it to a number and let's those babies chat, shake hands and do whatever PCs and their kind do.
It's Archaic and Unintuitive?
You can take that to the data center or is it the server bank? Yes, it's old and cranky and doesn't like GUI front-ends. It wants you to write everything by hand on the command line.
Every time you make a change, it wants you to restart it. It says it doesn't want any more of a certain kind of record and then the people at Apache make their server do something cool and you have to put those deprecated record types back into the configuration files.
Guess what else. It's installed base is so big, it won't start migrating and upgrading anytime soon. Like those Big orgs that hate to change - you can add the Internet DNS system to that angry bunch.
Should I Buy a Book?
You can buy a book or take Ambien CR. Either way, you get plenty of sleep. Reading the book might cause irritable neck syndrome.
So, poke around the Internet and look for readable tutorials and howtos. Or wait and catch the rest of this series as we head into the underground caverns of resolver libraries, zone files, hints and local zones to mention a few.
Until then, enjoy.
Thanks to Keith Daniels for these.
- The Open Source version of DNS
- OpenNIC: Democratic Name System DNS
- Tutorials, Tips and Tricks, HowTo and other Articles
- DNS Concepts
- DNS HOWTO
- DNS tricks and tips
- DNS for Rocket Scientists
- Internet Domain Name Structure
- Domain Name System
- Men & Mice - DNS Resources
- Setting Up Your New Domain Mini-HOWTO
- How to Use Domain-Based Blacklist Zones
- Bind and Dnsmasq
- freshmeat.net: Project details for Dnsmasq
- Configuring BIND with Webmin - RimuHosting
- BIND 9 Administrator Reference Manual
- Berkeley Internet Name Domain (BIND)
- Free DNS hosting- When you are learning, sometimes it is real handy to have a free backup for a while.:-)
- The Public DNS Service
- List of free DNS hosting sites
- Another list of free DNS hosting sites
- Setting up Dynamic DNS at Home is a good way to learn without breaking anything important. :-)
- How To Set Static and Dynamic DNS for Your ISP
- Free Dynamic and Static DNS
- Dynamic Network Services
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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- SUSE LLC's SUSE Manager
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide