The following Frequently Asked Questions (aka "FAQs") address the most common support questions that we receive. If these FAQs still do not answer your question, please contact us via the options on the "Contact Us" page of this web site.
The Domain Name System (aka "DNS") is the backbone of the Internet, translating IP addresses like 192.168.0.1 to domain names like www.google.com and mail.microsoft.com, etc. If DNS is down and you type www.microsoft.com into your web brower, you won't get anywhere because you can't do a lookup to find out where to go in order to reach www.microsoft.com.
The DNS tool in NetToolz can be used for several purposes. The two most common are:
1. To verify that the DNS information being returned for a given domain is correct. If you've made an update to DNS, this tool will query DNS to get a response and see if the update has taken effect yet.
2. To see if you can get a DNS hit at all... this is a quick way to determine the cause of a server outage. Once you know WHOIS info is fine and the domain is still properly registered and pointing to the right DNS Server, you can use the DNS Lookup utility in NetToolz to verify that you can actually GET a DNS lookup for the domain, and that the information is actually correct and accurate.
PING is a basic TCP/IP utility that just checks to see if a host/domain is reachable. If WHOIS and DNS all look good, a PING will be useful in helping to determine if the server's up and responding.
A caveat to note is that it's becoming increasingly popular to set firewall to "eat" PING (also known as ICMP) request packets instead of responding to them. This is considered a security benefit. Why help hackers by letting them know the server is there and listening? Just eat the packet and it makes it harder for them to figure out if there's a server there that's just not responding, or if there's just simply no server there. So the useful of PING is limited by the implementation of it. If a server (and/or its firewall) do not respond to PING requests, then a PING is of little use. For all servers that DO respond to PING requests, this utility will show whether or not the server hardware is up and running and connected to the internet, as well as provide diagnostics on how long the round trip took, which gives insight into possible network slowdowns along the route between you and that remote server.
Reverse DNS is one of the lesser understood elements of DNS, but it's very critical in certain cases -- primarily with email. More and more, mail servers are being configured to check the reverse DNS entries on any incoming email. This is an anti-spam authentication procedure. The reasoning behind it is straight forward: you can't fake a reverse entry anywhere near as easily as you can fake a normal "from" address in an email. So mail servers getting an incoming email supposedly from, say, Bill Gates at Microsoft.com will take the IP address it's talking to and do a REVERSE DNS lookup to see if that IP address really resolves back to microsoft.com (as an example). So if you take a domain name and resolve it's IP and then do the reverse, they should always work out to the same.
So what does this mean to us? It means REVERSE DNS is a good "first-line of defense" thing to check on if your mail server is having lots of email blocked. If you can't seem to send email through, make sure your REVERSE DNS is set up properly. Enter an IP address and NetToolz will tell you what your REVERSE DNS response is. If it's not correct, this gives you a lead to investigate!
Admittedly, WHOIS is becoming less useful over time as more and more people opt for "private registration" and block their details from being publicly displayed. But WHOIS can be helpful for diagnosing server outages. When a web server isn't responding yet you're sure the server is up and running, for example, we typically like to "start at the beginning" to so speak, and eliminate variables. We walk the chain from end to end, starting with a WHOIS.
First, is the domain still registered? I can't tell you how many times a customer lets the domain expire and doesn't realize it. They just call to complain when the web site "...is down." A WHOIS lookup will tell you the expiration on the domain name. "Ah! The domain expired. That's why!"
Next, if that all looks good and the domain is still registered to the proper owner and NOT expired yet, then we can look at the DNS Server entries. Are they pointing to the right DNS servers like they should? We've seen several instances where the registrar has a hiccup and DNS Server values to changed. Instead of pointing to your own internal DNS servers, they suddenly point to a generic DNS server at the registrar (such as NS27.REGISTER.COM, etc.) That's a problem because that DNS server is not configured with the right DNS information! So this tells you to log into your domain registrar and reset the DNS Server values to point to the proper DNS servers.
WHOIS can also help you trace down the owner of a domain if you need to contact them for some reason, provided they haven't chosen options to obscure their contact information which, unfortunately, is becoming increasingly prevalent. In that situation, there's nothing we can do about that -- we can only query and report on what the WHOIS servers are willing to show.