4 Security Considerations
Because the string "0x123" is a valid extended host name, there might be security issues depending on how client software interprets such strings. For example, as discussed in [ICANN], the inet_addr() method of the classic sockets Application Programming Interface (API) will interpret these strings as string representations of an IP address, and as discussed in [RFC3493] section 6.1, the getaddrinfo() method of the sockets API will perform a simple conversion of strings accepted by inet_addr(), instead of trying to resolve the name using any type of name resolution service. This could redirect the client software to an address other than an address registered for that host name. As such, great care needs to be taken before using an extended host name that could be interpreted as a hexadecimal number.