Home
>
Web Hosting
>
Fun with DNS: Three Useful Commands

Fun with DNS: Three Useful Commands

The DNS is a distributed, hierarchical database where authority flows from the top (or root) of the hierarchy downward.

When thinking of the structure of the DNS, imagine an inverted tree. Each branch of the tree is within a zone of authority; however, multiple branches of the tree can be within a single zone.

The software (Bind being the most common) that stores domain name information is called a domain name server. A single name server can be authoritative for multiple zones. All zones have a primary master and a secondary master name server that provides authoritative responses for their zones.

If you query a name server not authoritative for a particular zone, that name server will most likely have up-to-date information. This is because zone information propagates throughout the Internet at regular intervals, and name servers cache zone information for which they are not authoritative.

DNS Commands

There are three crucial commands that can put all the DNS information you need at your fingertips. The way to use this article is to try each of the commands listed on a domain name, so you can see what the output looks like. Learn by doing!

Zone file database records divide DNS information into three primary types: NS (Name Server) records, MX (Mail Exchange) records, and A (Address) records. NS records indicate the name servers. MX records indicate the hosts that handle e-mail delivery; the priority (pri) number indicates the order in which mail servers are used, with the lowest number receiving the highest priority. The A (Address) records map hostnames to IP addresses, the real names of machines.

host

This is the simplest of the DNS commands. It is a quick way to determine the IP address of a hostname:

: host www.your-domain-name.com

The -a option will return all of the DNS information in verbose format.

: host -a www.your-domain-name.com

Now that you know the IP address for www.your-domain-name.com, try a reverse lookup.

: host IP-ADDRESS

dig (domain information groper)

This command gathers and returns DNS information in a format the name server can use directly. You will find it easy to query specific name servers with dig.

You can quickly determine the Name servers of your host or any other host:

: dig ns your-host.com

Then you check your (or another) website against the host's name servers:

: dig www.your-domain-name.com @ns.your-host.com

Dig can provide output that is in the same format as the zone file itself. Here is how to get the whole zone file:

: dig any your-domain-name.com

Here are the most useful dig query types: dig any (gathers all DNS information), dig ns (gathers name server information), dig mx (gathers mail exchanger information) and dig a (gathers network address information).

The dig command can also do reverse lookups with output formatted for the zone file:

: dig -x IP-Address

nslookup

You can use this tool as a single line command, or you can use it interactively, which distinguishes it from the other DNS commands. Once you have started nslookup, type set all to list the default options. As with dig you can choose the server (name server) you want to query, and you can decide the type of DNS information on which to focus.

Just as you can issue commands to nslookup interactively, you can also change the initial defaults by starting a .nslookuprc file. The format of the .nslookup is one command per line:

set type=NS
set domain=srvns.your-host.com
set timeout=10

Conclusion

These three commands can provide you with most of the information you need about your domain names. They are powerful tools, and this article should provide you enough information to get started or offer a quick refresher if you already use these commands.

About the Author:

Dan Forootan founded ez publishing, inc. in 1998. EZ Publishing's ez publishing, inc. provides the essential tools for using the Web as a marketing tool. The package includes web hosting, the ez publishing, inc. solution. Please email questions or comments about this article to ez publishing, inc.. Thank you.

shuttle to Midway Beardstown .. Lockport Chicago limo O’Hare

In The News:

The FBI has issued a warning that scammers are impersonating doctors, police and banks using spoofed numbers as "smishing" texts surge nationwide.

Communities with unreliable internet service stand to gain after Amazon's Project Kuiper launched its first full batch of satellites into orbit April 28.

Tech expert Kurt “CyberGuy" Knutsson says unsubscribing from spam might actually backfire. Learn when to avoid it and stop junk effectively.

Tech expert Kurt “CyberGuy" Knutsson talks about how the first nonstop beating heart transplant, called zero ischemic time, at Taiwan hospital changes surgery.

Kurt “CyberGuy" Knutsson: FBI warns of "time-traveling" hackers.

Kurt “CyberGuy" Knutsson talks about a soft, vine-like robot called SPROUT that aids safe survivor rescues in collapsed buildings.

Health insurance giant Blue Shield of California confirmed it had been sharing private health data of 4.7 million users with Google for three years without even realizing it.

Delta and JetZero’s blended wing body aircraft marks a meaningful step toward a cleaner, quieter and more efficient future for air travel.

Recent reports show many common passwords can be cracked in literally seconds. Kurt the CyberGuy explains how to strengthen your passwords.

Stay up to date on the latest AI technology advancements and learn about the challenges and opportunities AI presents now and for the future.

Iron, a robot that stands 5 feet, 8 inches tall and weighs 154 pounds, combines advanced artificial intelligence with human-like movement and exceptional vision.

Hertz, the rental car giant, recently confirmed that customer information was exposed through a cyberattack on one of its software vendors.

There are a number of features with AirPods you may or may not know about to take your listening experience to the next level. Kurt the CyberGuy explains.

These 35 Chrome extensions have privacy and security concerns. Tech expert Kurt “CyberGuy" Knutsson says to delete them now.

Tech expert Kurt “CyberGuy" Knutsson says 329,000 mph fusion rocket promises to be fast, disruptive and enable deep-space missions.

Stay up to date on the latest AI technology advancements and learn about the challenges and opportunities AI presents now and for the future.

Tech expert Kurt “CyberGuy" Knutsson says a new autonomous AI is a game changer that also raises privacy risks. Is your data safe?

Tech expert Kurt “CyberGuy" Knutsson says robots and drones are revolutionizing fruit farming with faster picking and smarter handling.

Landmark Admin revises May 2024 cyberattack scope to show twice as many people were affected. Kurt “CyberGuy" Knutsson gives tips to help stay safe from an insurance data breach.

Tech expert Kurt “CyberGuy" Knutsson talks about how Yamaha’s hydrogen outboard motor could revolutionize boating with zero emissions.

Tech expert Kurt “CyberGuy" Knutsson reveals how to memorialize or remove a deceased loved one’s Facebook account and protect their digital legacy from misuse or scams.

Tech expert Kurt “CyberGuy" Knutsson says an Apple Watch saved psychiatrist Amanda Faulkner by detecting deadly leukemia early.

Scammers and fraudsters are increasingly targeting the most vulnerable, especially nursing homes and the personal data of their residents. Kurt the CyberGuy has safety tips.

Infected USB flash drives can spread malware among multiple organizations in ways that can easily bypass traditional security systems.

With a fully automated warehouse system and AI-powered robots, Ocado's Hive picks, packs and delivers grocery store orders in just a few minutes.

Fun with DNS: Three Useful Commands

Web Hosting