The DNS provides us with a means of translating hostnames into IP addresses. If a DNS server is not specified at all, then the host will not be able to take advantage of DNS services. If the correct DNS server is not specified (for example, if the primary server is incorrect), then DNS resolution can take longer than necessary, thus giving the impression that internet access is slower than it actually is.
A good indicator that DNS configuration is incorrect is if you can ping a site if you specify the IP address, but the ping fails when you specify the hostname (and ping returns an unknown hostname or a similar error). If this happens, you should definitely check the DNS configuration, first on the host and then on ...
