NT DNS forward server can not find 163.com's MX record in the cache.

From: Tianjin Hu Hao (tjhuhao_at_sina.com.cn.discuss)
Date: 11/05/04 

Date: Fri, 5 Nov 2004 13:49:13 +0800

Hi all,

I am using a NT DNS server in my internal network, the query to DNS server
is forwarded to headquarter's DNS server and ISP's DNS server.

The problem is: When I clean the DNS server's cache, I can find 163.com's MX
record if I query my DNS immediately, But then I can not find it again once
163.com's record is cached in the NT DNS cache. And 163.com is a very big
free email provider in China which is impossible for me to ignore the error.

Some background:

1. There is no problem when I use nslookup to test 163.com's MX on my HQ's
DNS and ISP's DNS.

2. I have found only 163.com's MX query problem on my DNS server. Other
queries are OK.

3. The structure of 163.com's MX is quite strange. There is a MX record, MX
record's result is m***.163.com, then there is a CNAME record map the
m***.163.com to m***.mail.163.com, finally there is an A record map the
m**.mail.163.com to IP address. Mail exchanger record for other site is just
a MX record, then an A record map it to IP address. there is a CNAME record
extra for 163.com.
for example:
first
    163.com MX preference = 50, mail exchanger = m208.163.com
then
    Name: m209.mail.163.com
    Aliases: m209.163.com
finally
    Name: m209.mail.163.com
    Address: 202.108.44.209
I think the structure of 163.com's MX record might lead to this error.

4.From my DNS server's capture packets, after the cache is cleared, when the
client query my server at the first time, my server will query HQ's DNS
"Standard query MX 163.com", then HQ's DNS returned "Standard query response
MX 50 m207.163.com MX 50 m208.163.com MX 50 m209.163.com ......", then my
server will return it to the client.

But after the first time query, my server will query HQ "Standard query A
m207.163.com", then HQ return "Standard query response CNAME
m207.mail.163.com A 202.108.44.207" to my server, then my server keeps on
query HQ m208,m209....163.com's A record, but my server doesn't return
anything to client.

Looking forward for somebody can help me. Thanks a lot for your help!

Relevant Pages

  • Re: SBS 2003 R2 MX and A records
    ... Now's about the time I'd be assuming control of the DNS records for the ... Query: stetsonbaptistchurch.org. ... The name server "ns2.siteprotect.com" refused to answer a query ... I am afraid the IT Lady just called the old hosting company ...
    (microsoft.public.windows.server.sbs)
  • Re: DNS
    ... If there is no name server at address $FOO, sending a DNS query will ... the resolver waits for a response ...
    (linux.redhat)
  • Re: DNS
    ... If there is no name server at address $FOO, sending a DNS query will ... the resolver waits for a response ...
    (linux.redhat)
  • Re: Newbie Question RWW From out side
    ... ARRRRRGGGGHHH, you named the AD DNS whatever.com, dumb. ... Query: expressmortgageservice.com. ... Query time: 38515 ms. Server name: n/a ... setup this sbs 2003 with 10 clients. ...
    (microsoft.public.windows.server.sbs)
  • Recursion?
    ... I use Server 2003's DNS to service about 8 computers on a home network. ... Standard query PTR 178.11.122.12.in-addr.arpa ... Standard query response PTR gbr1-p20.wswdc.ip.att.net ...
    (microsoft.public.windows.server.dns)
Loading