lwresd

Lightweight Resolver Daemon (lwresd) is a client-side name caching daemon, used to greatly speed up application DNS lookups. It …

– gives you faster responses and isolates you from upstream network or DNS problems that could drop your DNS queries
– protects the central, shared DNS resolver service from rogue and aggressive clients.
-is part of the BIND name server package, and is shipped with the BIND binary packages.
– is the default name caching daemon on RHEL5 hosts

 

This translates to:

  • /etc/hosts is checked first
  • lwresd is queried next. It will check its cache and query the DNS resolver fleet if necessary
  • If lwresd fails to answer the host will fallback to making direct DNS queries to the resolvers

The problem

How do you query lwresd, and only lwresd? dig or nslookup are no good. They can only talk DNS (not lwres). getent goes through the full gamut of libnss sources so may be answering from the hosts file or falling back to DNS.