DNSQueries provides network tools and lets you make every needed network test, such as domain health tests, RBL checks, dns lookup, ptr queries, host geographical. Use dig to Perform Manual DNS Queries. Updated Tuesday, May 17th, 2011 by Linode. Contribute on GitHub. This example traces a DNS query for the domain www.example.
Rick, thanks for your reply. Here's a sample of a manual DNS query that causes the issue (sorry, answers in German) C:\Windows\system32>nslookup Standardserver: s1.
Troubleshooting DNSChapter 1. DNS on Windows 2. Second Edition, published by O'Reilly & Associates, Inc."Of course not," said the Mock Turtle. Why, if a fish came to me, and told me he was going on a journey, I should say, 'With what porpoise?'" "Don't you mean 'purpose'?" said Alice.
Re: Reverse DNS lookup at telnet. Daniel Martin at cush 01:17:46 -0000. so a reverse DNS query is never necessary. More information in hosts_access(5). How do debug DNS name resolution? (nslookup works, but telnet doesn't). QUERY, status: NOERROR, id: 22229;; flags: qr rd ra; QUERY: 1, ANSWER: 1. IP Addressing: DNS Configuration Guide, Cisco IOS Release 15M&T -Configuring DNS. Manual de usuario Telnet TriwaveSTB. Cliente/Servidor DHCP, DNS Relay, ARP. Otras características: UPnP. Cliente RADIUS. Filtrado IP. NAT/PAT. Control Paterno. Host is a simple utility for performing DNS lookups. It is normally used to convert names to IP addresses and vice versa. When no arguments or options are. BIND is the Berkeley Internet Name Domain, DNS server. It is wildly used on UNIX and Linux like oses. You can use following tools to troubleshoot bind related.
I mean what I say," the Mock Turtle replied, in an offended tone. And the Gryphon added, "Come, let's hear some of your adventures."In the last chapter, we demonstrated how to use nslookup to make queries. In this chapter, we'll show you how to use nslookup- -plus traditional TCP/IP networking tools like trusty ol' ping- -to troubleshoot real- life problems with DNS. Troubleshooting, by its nature, is a tough subject to teach.
You start with any of a world of symptoms and try to work your way back to the cause. We can't cover the whole gamut of problems you may encounter on the Internet, but we will certainly do our best to show you how to diagnose the most common of them. And along the way, we hope to teach you troubleshooting techniques that will be valuable in tracking down more obscure problems that we don't document. On This Page. Is DNS Really Your Problem? Checking the Cache. Potential Problem List.
Interoperability Problems. Problem Symptoms. Is DNS Really Your Problem? Before we launch into a discussion of how to troubleshoot a DNS problem, we should make sure you know how to tell whether a problem is caused by DNS, not by another naming service. On Windows hosts, figuring out whether the culprit is actually DNS can be difficult. Windows supports a whole panoply of naming services: DNS, WINS, HOSTS, LMHOSTS, and more. The stock Windows 2.
You can run nslookup on a Windows 2. How do you know where to put the blame? First, you need to consider what kind of program is having the problem. If it's a TCP/IP client, such as telnet or ftp, the possible culprits are DNS and the HOSTS file. If it's a utility that supports Net. BIOS naming, such as net (as in net use), the likely suspects also include WINS and the LMHOSTS file.
Other clients, such as ping, that also take either a DNS name or a Net. BIOS name as an argument can use any of these naming services. Next, consider the order in which Windows uses the naming services. You should look through the various services in that order when troubleshooting the problem.
These hints should help you identify the guilty party or at least exonerate one suspect. If you narrow down the suspects and DNS is still implicated, you'll just have to read this chapter. Checking the Cache.
As we've said earlier, you can check the contents of your name server's cache with the DNS console. This can come in handy if you suspect that your name server has cached bad or out- of- date data from another server. To inspect a server's cache, click the plus sign to the left of the name of the server in the DNS console's left pane. You'll see a folder named Cached Lookups.
Either click on the plus sign to the left of it or double- click the folder icon or the label to expand the next level. This shows you the top- level domains for which your name server has cached data. Expand your way to the domain name to which the cached data you're looking for is attached. In Figure 1. 3- 1, we've clicked our way down to acmebw.
As you can see in the right pane, our name server has cached three NS records and one A record for acmebw. If we double- clicked net and then acmebw, we could find the cached addresses of these name servers, too.
If you'd like to see the TTL on the cached data, double- click on a record in the right pane. Provided the DNS console is in advanced view mode (select View Гћ Advanced), the resulting window shows the record's TTL.
For example, in Figure 1. A record. Figure 1. The TTL on a cached record. Be sure to refresh the DNS console with Action Гћ Refresh or F5 before checking the TTL, or the TTL you see may be bigger than the current TTL. If you right- clicked the record, you may have noticed a Delete Record selection. Now there's something you can't do in BIND.
Using the DNS console, you can actually delete cached data record by record! If you know that some records in your name server's cache are out of date, you can delete them and let your name server pick up updated records from an authoritative name server. Potential Problem List. Let's go through some common real- world DNS problems. Many of these problems are easy to recognize and correct. We cover these problems as a matter of course- -they're some of the most common problems because they're caused by some of the most common mistakes.
Here are the contestants, in no particular order. Forget to Increment Serial Number.
This particular problem will occur only if you make changes to your zone data file by hand, without using the DNS console. The DNS console remembers to increment the serial number in the SOA record each time it changes zone data, so you don't have to worry about it. However, this also means that you probably won't be in the habit of updating the serial number, so you may forget when making that one- off manual modification.
The main symptom of this problem is that slave name servers don't pick up any changes you make to the zone on the primary server. The slaves think the zone data hasn't changed since the serial number is still the same. How do you check if you remembered to increment the serial number? Unfortunately, that's not so easy. If you don't remember what the old serial number was and your serial number gives you no indication of when it was updated, there's no direct way to tell whether it has changed. When you start the primary, it will load the updated zone data file regardless of whether you've changed the serial number. About the best you can do is to use nslookup to compare the data returned by the primary and by a slave.
If they return different data, you probably forgot to increment the serial number. If you can remember a recent change you made, you can look for that data. If you can't remember a recent change, you can try transferring the zone from a primary and from a slave, sorting the results, and using a file- comparison tool to compare them.
The good news is that, although determining whether the zone was transferred is tricky, making sure the zone is transferred is simple. Just increment the serial number on the primary's copy of the zone by double- clicking the SOA record in the DNS console and manually editing the serial number field. The slaves should pick up the new data within their refresh interval, or sooner if they use NOTIFY. Forget to Restart Primary Master Server. Like the last problem, you'll see this problem only if you make changes to your zone data files by hand. The DNS console adds and deletes data on the fly, so there's no need to restart your primary master name server. If you're not using the DNS console, though, you may forget to restart your primary master name server after editing a zone data file.
The name server won't know to load the new data- -it doesn't automatically check the file to see if it has changed. Consequently, any changes you've made won't be reflected in the name server's data: new zones won't be loaded, and new records won't percolate out to the slaves. To check when you last restarted the name server, scan the Event Viewer output for the last entry that looks like this. The DNS Server has started. The date and time on these events will tell you the last time you restarted the name server. If the time of the restart doesn't correlate with the time you made the last change, use the DNS console to stop and restart the name server and reload its data.
Check that you incremented the serial numbers on the zone data files you changed, too. DNS Server Loses Manual Changes. One final but important note about making manual changes: remember that the Microsoft DNS Server periodically updates its zone data files. Each time you make changes to a zone's data using the DNS console, a write is pending: before the DNS server exits, it must rewrite the zone's data file or it will lose the changes you made. Think of this as a dirty page in memory: the operating system must write it to disk before exiting. If you make a manual change to a zone data file while a write is pending, you'll mysteriously lose the change when the name server exits. Say you add delegation to a new subdomain of movie.
After you've made the change, you have to stop the server and start it again to get it to read the zone data again. But as the server exits, it rewrites the movie. If you're watching the Event Viewer carefully (like you should be), you'll see this message before the server stops. The DNS server wrote version 3. Once you force the server to rewrite its zone data files with Action Гћ Update Server Data Files, the server is in sync with the zone data files and doesn't have to rewrite them on exit. So, if you're going to make manual changes to the zone data files, you should either stop the server first (although that means your server won't answer queries while you make the change), or use the DNS console to sync the server with the zone data files and then make the change. Slave Server Can't Load Zone Data.
If a slave name server can't get the current serial number for a zone from its master server, you won't be warned about it initially. However, if the problem persists and the slave can't determine within the expire interval whether or not its data is up to date, it will expire the zone. On a Microsoft DNS Server, you'll see a message like this in the Event Viewer. Zone movie. edu expired before it could obtain a successful. The zone has been shut down.
Once the zone has expired, you'll start getting SERVFAIL errors when you query the name server for data in the zone. C: \> nslookup robocop wormhole. Server: wormhole. Addresses: 1. 92. Server failed. There are three leading causes of this problem: a loss in connectivity to the master server due to network failure, an incorrect IP address configured for the master server, and a syntax error in the zone data file on the master server.