# dnslookup, hash, hfetch, hostinfo, and SDR

dnslookup. dnslookup performs a DNS lookup of a hostname or a reverse DNS lookup of an address. It demonstrates how to use both the blocking and asynchronous methods of DNS lookups.

hash. hash computes the MD5 and SHA hashes of a file.

hfetch. hfetch is a simple HTTP file fetcher.

hostinfo. hostinfo prints information about the host including it's domain name and interfaces.

SDR. SDR prints multimedia session announcements. It demonstrates how to use multicast sockets in GNet. SDR will only work if your network supports IP Multicast. In fact, SDR is a good test for this. If the network supports multicast, SDR will print announcements after a few seconds, otherwise, it will print nothing.