Why must Comcast's DNS suck?

Dan Jenkins dan at rastech.com
Fri Nov 17 10:56:48 EST 2006


Pete Snider wrote:

> The problem we experience was email outage where outgoing email.  The 
> error
> message indicated that adelphia.net was not allowed to relay.  I'm 
> guessing
> that adelphia was relaying the switched customer's outgoing email to 
> comcast
> smtp servers and comcast was refusing the relay.  Talking to adelphia and
> comcast customer support was very comical.

We have several clients on Adelphia. We have seen varying behavior over 
the course of time:
1) all outbound port 25 traffic blocked no matter what the destination, 
including their own mail servers
2) port 25 blocked going to Adelphia's mail servers, but only if you 
were on Adelphia's network; port 25 access from the Internet worked 
fine; port 25 access to other mail servers was fine
3) randomly varying DNS changes such that sometimes Adelphia's mail 
servers resolved to Time-Warner's or Comcast's mail servers, but:
3a) Comcast's mail servers rejecting Adelphia traffic, even though the 
DNS pointed to it
3b) Time-Warner's port 25 traffic was not being rejected, just blackholed
4) port 110 and 143 traffic being dropped no matter what the destination

All with no notification of any changes, and useless technical support. 
Once, when I called Adelphia, they denied that either Comcast or 
Time-Warner were taking over ever.

Not that Adelphia's support was ever very good, in our experience.

-- 
Dan Jenkins (dan at rastech.com)
Rastech Inc., Bedford, NH, USA --- 1-603-206-9951
*** Technical Support Excellence for over a Quarter Century




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