[PLUG] Is there a DNS cache in the Comcast modem?

[King Beowulf]

On 09/20/2017 02:08 PM, Denis Heidtmann wrote:
> Snarky, yes, but I appreciate the advice.  I had a wireless router which
> you may recall from a previous post was blamed for a DNS poisoning event
> (likely erroneously.)  And I have been considering Ooma for a while.  It is
> time to do it.  Then getting my own cable modem will be simpler--more
> choices if voice is not needed.  And it does appear I have learned little,
> but not nothing, on this list.  Some people are slow learners.
> 
> But for curiosity's sake, does this modem have a DNS cache?

I still find it suspicious that I can't find your Arris TG1268T anywhere
on 3 search engines and Arris web site.  The router portion, which does
the DNS lookup, and is where you set the wifi info etc), is most likely
accessed via the base internal network address, typically 192.168.1.1
for example, and look for menu for Network and DNS.  There might be
something under Interfaces.  If the firmware is based on openwrt or
similar, it's most likely using dnsmasq, which uses a cache although the
default size "might" be set to zero.  restarting dnsmasq clears the cache.

Also, don't forget that browsers can cache dns as well. (Firefox
about:config look for "network.dnsCache")

> 
> I believe they do use the wireless in the modem to provide xfinity
> wireless, but I have been lead to believe it does not go under my bandwidth
> and data cap.  My laptop reports an xfinity wireless but I have been unable
> to connect to it.  Instead I connect to wireless using one I have named
> Comcastrrash in the Arris.
> 

Well, Bill W. responded to this. I will just add the trust must be
earned, something Comcast hasn't done IMHO. I solve the wifi issue by
not giving them access to "free" wifi.

-Ed