@ishi1234, If it was due to the delay in DNS propagation, it should likely have been solved by now. DNS propagation typically takes between 24 and 48 hours, though it can sometimes stretch to 72 hours in rare cases. You can raise a support ticket if you continue to face this issue, and they can check it on their end and reach out to Cloudflare regarding this if required.
Also, while configuring SSL certificates is a good practice for securing your landing pages, it's not directly related to the current DNS resolution error.
More to the point, at the current time lp.stressless.com is set up as an alias for 853-xwi-508.mktoweb.com.
There’s nothing wrong with the replication of that CNAME RR itself.
However, the CNAME 853-xwi-508.mktoweb.com does not exist now, so it’s clear that you need to open a support ticket:
; <<>> DiG 9.16.24 <<>> 053-xwi-508.mktoweb.com.
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 23966
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;053-xwi-508.mktoweb.com. IN A
;; AUTHORITY SECTION:
mktoweb.com. 894 IN SOA ns1.marketo.com. ops.localhost. 3040351596 300 300 604800 900