Is it normal that a subdomain's CNAME record is suffixed with my domain?

Question

I am using the Alternc control panel for shared hosting.

I am setting up a subdomain to point to github pages, as described here.

I need to point the CNAME record for my subdomain to .github.io, which I did with the alternc interface as seen in this image.

After waiting more than 24 hours, I got this message from github:

CNAME record should point to `your-username.github.io`, but it does not.

In effect, when visiting http://mxtoolbox.com/SuperTool.aspx?action=cname%3asommet.terredesjeunes.org&run=toolpage#, the CNAME record seems to be set to:

alberto56.github.io.terredesjeunes.org

not

alberto56.github.io

Same thing when running dig:

$ dig sommet.terredesjeunes.org +nostats +nocomments +nocmd
...
;sommet.terredesjeunes.org. IN  A
sommet.terredesjeunes.org. 86400 IN CNAME   alberto56.github.io.terredesjeunes.org.

I would be expecting to see the CNAME being alberto56.github.io, not alberto56.github.io.terredesjeunes.org. Is this a glitch with alternc, or am I not understanding something?

Thanks!

Albert.

Answer 1

Full DNS names need to end in a ., the root zone, otherwise the current zone is appended to the name. So, you want to set your CNAME to alberto56.github.io. with the terminal period to indicate that resolution should start from the root zone.