Constant DNS_MAX_NAME_SIZE 

pub const DNS_MAX_NAME_SIZE: usize = raw::DNS_MAX_NAME_SIZE; // 255usize

Longest DNS name that can be queried, in wire format, in bytes.

The wire format is one length byte per label plus the label itself, so a name takes one byte more than its dotted form. 255 is the most the DNS protocol allows.

This is a limit with and without alloc. Default: 255.