cancel
Showing results for 
Search instead for 
Did you mean: 

Strange IP address assigned - to do with conflicting DNS servers?

grahamt
Rising Star
Posts: 567
Thanks: 13
Registered: ‎05-04-2008

Strange IP address assigned - to do with conflicting DNS servers?

Yesterday evening I had an internet disconnect and, after my router indicated I was reconnected, I found that I couldn't reach any sites beyond the router. Looking at the router log, I saw that the IP address that had been assigned was 172.20.n.n (where 'n.n' are the same numbers as the last two numbers of my router's 192.68.n.n internal IP address - coincidence?). Once normal service had been resumed (after another disconnect/reconnect cycle) I checked this IP address and found that it's in one of the other ranges used for private internal addresses.
I've got a vague memory that, with FTTC, there can be a conflict between Plusnet's DNS servers and BT's in certain situations. The workaround is to manually input the addresses of Plusnet's DNS servers into the router settings, which I did a while back and have since kept to. Is the 172.20.n.n IP address one that could have resulted from such a conflict, or does it look like a different problem?
Graham
2 REPLIES
Community Veteran
Posts: 26,744
Thanks: 954
Fixes: 10
Registered: ‎10-04-2007

Re: Strange IP address assigned - to do with conflicting DNS servers?

It means the BT systems failed to connect you to Plusnet.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
grahamt
Rising Star
Posts: 567
Thanks: 13
Registered: ‎05-04-2008

Re: Strange IP address assigned - to do with conflicting DNS servers?

Thanks. That's useful to know. If it happens again and I notice in time I'll disconnect and reconnect.