Is anyone else seeing these problems or is it just me?

sh-3.2$ nslookup twitter.com
;; Got SERVFAIL reply from 121.98.0.1, trying next server
;; Got SERVFAIL reply from 121.98.0.1, trying next server
Server:        121.98.0.2
Address:    121.98.0.2#53

** server can't find twitter.com: SERVFAIL

sh-3.2$ nslookup geekzone.co.nz
Server:        121.98.0.1
Address:    121.98.0.1#53

Non-authoritative answer:
Name:    geekzone.co.nz
Address: 104.25.178.9
Name:    geekzone.co.nz
Address: 104.25.179.9

sh-3.2$


Looking here, it appear that I'm using the correct DNS server ip addresses.
The problem seems to affect just a few domains - at least twitter.com and perhaps others.

My mobile can find twitter.com using vodafone 3G/4G and I can find twitter.com on Orcon DSL if I change the dns server.

sh-3.2$ nslookup
> twitter.com
;; Got SERVFAIL reply from 121.98.0.1, trying next server
;; Got SERVFAIL reply from 121.98.0.1, trying next server
Server:        121.98.0.2
Address:    121.98.0.2#53

** server can't find twitter.com: SERVFAIL
> server 8.8.8.8
Default server: 8.8.8.8
Address: 8.8.8.8#53
> twitter.com
Server:        8.8.8.8
Address:    8.8.8.8#53

Non-authoritative answer:
Name:    twitter.com
Address: 104.244.42.65
Name:    twitter.com
Address: 104.244.42.1
>

I'd expect that others will find the same problem for twitter.com, but it would be good to have it verified.

Edit: fixed a lot of typos.