DNS Traffic: TXT records spike


#1

From time to time I see a spike in DNS requests, in particular TXT requests. What could be the reason?

Screenshot: http://take.ms/nmNDl


#2

I most often associate a TXT record spike with a bulk mailing being sent out (whether by you or spammers forging your domain in the mail from). Since SPF records are stored as TXT records an email sent to a large number of users will cause their MTAs to perform a corresponding/proportional number of lookups.

I just rechecked the screenshot and the corresponding number of Mx record and A record lookups makes that seem likely in this instance.


#3

Interesting! We are sending out newsletters regularly, so that makes perfectly sense.

Thanks @cscharff !