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kosiac
join:2001-01-10
Dayton, OH
| DNS in RT314 not working correctly I have discovered that my netgear rt314 router's DNS does not seem to be handling MX record lookups. I have my PC set to use the RT314 as my DNS host. If I use nslookup from the pc and try to do an MX record lookup I get an unknown error. When I change my PC to use the DNS servers that the router is using, then the nslookup I mentioned works correctly. I am using the 3.25 version of firmware with the router.
Any ideas on what may be causing this?
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- Dayton, Ohio, The TRUE Birthplace of Aviation - | |
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kosiac
join:2001-01-10
Dayton, OH
| Re: DNS in RT314 not working correctly They way I understand it, (I am by no means a DNS expert), Mail Exchange Records (MX) records are used when sending email. They allow all mail for a domain to be routed to one host. There are Address Records (A) also, those are used when resolving the domain name to an IP address. Both record types are part of the DNS entry for a domain.
My SMTP server on my LAN needs to query the DNS for the MX record for a domain. For example, when I send an email from my email client, it goes to the SMTP server on my LAN (set in my client). SMTP server will query DNS for the Mail Exchange (MX) record. This is what isn't working when my router is involved in query. SMTP get's the MX info and the uses the data to forward the email directly to the email recipient's domain. If I query DNS for an Address record (typical dns lookup like when you browser is looking for an IP) it works fine regardles if the router is involved or not.
To kind of see what I mean, go to a command line in NT/windows 2k/unix. Type in nslookup. type in microsft.com and hit enter. You will se the Address record(s). Then type in "set vc" hit enter then type "set q=mx" and hit enter. This will change the query type to MX. Then type microsoft.com and hit enter. You will see the Mail Exchange record.
Using the example above, if the router is involved, an I do the mx query, it fails and nslokup returns "*** [192.168.0.1] can't find microsoft.com: Unspecified error". If I use the DNS from my ISP, I get the proper results.
I have tried rebooting he router and powering it off.
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- Dayton, Ohio, The TRUE Birthplace of Aviation - | |
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kosiac
join:2001-01-10
Dayton, OH
| Re: DNS and Netgear... Interesting. For me, the virtual circuit only fails when querying the router and not the external dns. I tried this from both my systems(XP and 2K). If I turn it off (it is by default in nslookup) the query works fine to the router.
Can you explain what "Virtual Circuit" actually means? I can not find a good definition of it.
Do you think I should I reload firmware or just restore the factory defaults or both?
True the router is not an authoritative source for DNS, I thought it acts as a DNS proxy, and it maintains a table with cached DNS entries and various other elements. I thought it was more than a passive pass through to the authoritative sources.
[text was edited by author 2002-07-31 00:43:42] | |
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kosiac
join:2001-01-10
Dayton, OH
| Re: DNS and Netgear... Answered one of my own questions. Found this about Virtual Circuit:
DNS uses IP port number 53 and can either use UDP or TCP for transport. Generally, UDP (limited to 512 bytes) is used for queries and responses i.e. Lookups but, TCP (virtual circuit) has to be used for Zone Transfers as the data shared between authoritative servers handling particular zones needs to be reliable.
Possibly the vc is unsupported on the Netgear.
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- Dayton, Ohio, The TRUE Birthplace of Aviation - | |
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SYNACK
Just Firewall It
Premium,Mod
join:2001-03-05
Venice, CA
 ·Comcast Formerly ..
Host:
Networking
Virtual Private Ne..
Netgear
ZyXEL
| Re: DNS and Netgear... Yes, the router only listens for 53/UDP, not TCP.
try:
ip tcp stat
ip udp stat
... to see all services running on the router.
Simply configure with the external DNS servers directly, then it's just another outgoing TCP connection.
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Where in the world is LA/OC ? | |
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Rizal7
Best Cheater Wins
join:2001-02-21
Norway
| Re: DNS in RT314 not working correctly said by danielrm26:
So, going back to the original problem, why would an MX record lookup fail just because you couldn't correspond with a DNS server over TCP?
If you query the DNS proxy in the 314 with TCP it will never see your query because it does not listen for TCP connections, only UDP. Because its not a DNS server, but just a 128 line proxy and if the FQDN you want to lookup is not in the table it will query a DNS server for you.
The 314 was never intended to support zone transfers etc.
Go to CI mode and type the commands Synack listed, those will show you which ports the 314 is listening on for TCP and UDP connections.
Also try ip dns stats disp
Now weather your software uses TCP for mx record lookup is another issue.
Rizal
[text was edited by author 2002-07-31 03:22:01] | |
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kosiac
join:2001-01-10
Dayton, OH
| Re: DNS and RT314... I used a tool that monitor network connections (from sysinternals) and it show that inetinfo (windows smtp server is part of iis) was making TCP connections to 65.24.0.167, my external DNS server.
I posted in the windows group here to see if anyone know why Windows SMTP would use TCP. Also posted in the windows smtp NNTP group as well.
We will see.
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- Dayton, Ohio, The TRUE Birthplace of Aviation - | |
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kosiac
join:2001-01-10
Dayton, OH
| Re: DNS and RT314... I got a reply back on my post to the Microsoft newsgroup. The answer was "Unfortunately for Window 2000 you are stuck with TCP only.", according to a MS SMTP test engineer. Oh well, I will just use external NS hoss.
Thanks for the inputs.
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- Dayton, Ohio, The TRUE Birthplace of Aviation - | |
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DNS issue with RT314...