DENIC, the German domain registry, has massively upgraded and expanded its global name-server network over the past few weeks. Now that the changes have been entered into the domain system's root servers and the final optimizations made, the switchover is complete and the new configuration is in regular operation. At least another five new name-server locations are to be added by the end of 2005; these are to be set up in Eastern Europe, South America, Africa, Southwest Asia and the Pacific. This marks DENIC's response to the explosive growth in demand for name-server resources that has come about as a result of the increasing use of the Internet. The number of queries that DENIC's name servers are called upon to answer now stands at 700 million per day - twice as many as only a year ago.

Name servers are used to match domains (such as denic.de) to computers' numeric IP addresses. They are thus indispensable for calling websites or sending e-mails. All this information is updated several times a day (currently generally eight times a day) for domains ending in .de.

By upgrading its network, DENIC has been able to increase its capacity further and to improve stability. Each of the locations thus now has not just one name server but a cluster of three name servers with an additional computer controlling the others. Load balancers ensure that all incoming queries are distributed evenly over the three servers, so that the capacity utilization of the individual servers never exceeds five percent in normal operation. Different types of server (SUN and IBM machines) are employed, using different processors, operating systems and name-server software (BIND in Versions 8 and 9 and NSD). This three-fold diversification ensures that, if dependability problems are encountered with one component, sufficient capacity will still be available to handle all queries without any degradation in response times.

The name servers located in Berlin, Frankfurt, Vienna, Stockholm, Elmsford NY and Tokyo are operated in so-called anycast mode. This means that they can all be reached at the same IP address, even though the computers themselves are in different geographical locations. A query is always automatically routed to the name server that can respond the fastest. Since the anycast locations are all accessible at just one address (194.246.96.1 in the IPv4 network) and hence under just one name (z.nic.de), the number of name-server entries in the root zone has nominally fallen. In future too, following the expansion of the DENIC name-server network, it will thus be possible for all the name servers to be returned to the enquiring application (web browser or e-mail client, for example) via the network in a single name package. DENIC has additionally brought a second name server into operation in the IPv6 network; it is located in Vienna.