In additions to the responses from @CrazyTom2k2 and @Shazzkid a bit more detail here https://www.networkworld.com/article/3268449/what-is-dns-and-how-does-it-work.html
A guide to the best public DNS servers here https://www.techradar.com/uk/news/best-dns-server
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 5.0,Android 13 .