Why does LLMNR recommend TTL=255 for UDP queries and responses?
LLMNR UDP queries are sent to a link-local multicast address. Properly functioning routers should not forward packets destined to a link-scope multicast address beyond the local scope. Therefore UDP queries sent to a link-scope multicast address can have the TTL set to any value without fear of leakage beyond the local link. For UDP responses, the TTL may be set to any value. TTL=255 is recommended in UDP queries and responses, for compatibility with implementations that check TTL=255 on receipt.
