What order do split TXT records get assembled in?

Solution 1:

The parts are always reassembled in order. The 255 character limit is on parts of the TXT record. Without EDNS0, there is an addtional 512 byte limit for a UDP response. However, this does not apply to a TCP response.

Solution 2:

Also, you may encounter a problem with AWS Route53, where

IN TXT "v=spf1 .... first""second string..."

IS treated as an equivalent to

IN TXT "v=spf1 .... firstsecond string..."

But if you use spaces... the following WILL FAIL:

IN TXT "v=spf1 .... first" "second string..."