sha256sum debian-11.11.0-amd64-netinst.iso Compare the output with the SHA256SUMS file from the download folder. If they match, your ISO is perfect.
Here’s an interesting and useful text about downloading the Debian 11 (bullseye) 64-bit ISO, including tips most guides skip: download debian 11 iso 64-bit
Long Term Support (LTS) through the Debian LTS project extends until 2026-08-31 (and then ELTS until 2028). For production servers avoiding major version upgrades, 11 is still a rock-solid choice. Would you like the direct command-line wget example for the netinst ISO, or help with creating a bootable USB from Linux/Windows/macOS? sha256sum debian-11