Chapter: Overview Up Main page Chapter 2: Zones Page 

1 Overview Page

This is available at NodeWorx ▷ System Services  ▷ DNS Server  ▷  Overview

1.1 DNS Server information

The version of the DNS server installed. By default, InterWorx uses DJBdns, a DNS implementation created by Daniel J. Bernstein in response to security holes present in some older standard DNS software, BIND.

1.2 Default DNS Servers

Primary DNS, Secondary DNS, Tertiary DNS
These are the nameservers that you want your InterWorx server to handle. A typical set-up includes at the very minimum two named DNS servers, with a possibility of up to three for more redundancy’s sake. This is what is set as the nameservers for new SiteWorx accounts created on this server.

1.3 Zone Defaults

These are advanced DNS settings that control the timeout and expiration times for DNS lookups. The default settings should work for a majority of users.
  1. Refresh time sets the number of seconds that a slave will cache the record before re-checking the primary server. Recommended values are between 1200 (twenty minutes) and 43200 (twelve hours).
  2. Retry Time sets the number of seconds to retry a refresh after the previous refresh attempt fails. Recommended values are between 180 (three minutes) and 900 (fifteen minutes).
  3. Expire Time sets the number of seconds for refresh and retry attempts before the server will stop serving the zone. Per RFC 1912, recommended values are between 1209600 (two weeks) and 2419200 (four weeks). This value is only used by slave servers.
  4. Minimum TTL sets how often dns servers check back for changes to existing records. This is usually the server default but can be changed on an A Record by A Record basis.

1.4 SOA Serial Format

Advanced setting for DNS record formatting.
SOA is a “State of Authority” record that is required for all DNS zones that includes source host, contact email, refresh time, retry time, expire time, and minimum TTL (time to live) for the zone. InterWorx provides two options for the format of these records, the Tinydns default and a different recomendation by a DNS standardization organization. Either setting is acceptable in the majority of situations.

1.5 Active DNS Services

figure dns-activednsservices.png
This box holds all of the system IPs and determines whether or not a DNS service is installed, running, or halted. Similarly, DNS services can be removed and installed on a per IP basis. Lastly, the DNS cache can be flushed on this page. When a DNS serice is installed on an IP address determines whether that IP will respond to DNS requests on that IP. You may not need to have DNS services installed on each IP if that IP is not set to handle DNS requests. This is defined on a per-IP basis for large servers that have multiple IPs on them that may not necessarily be assigned to handle DNS queries.
It is typical for DNS servers to cache DNS queries in order to increase performance so that the server does not have to make network queries every time that DNS service is asked for information. You may wish to flush the DNS cache to make the service “forget” previously-saved DNS requests if it is reporting wrong or out of date information.

1.6 IP Addresses Without DNS Services.

If a DNS Service gets uninstalled for any reason on a system IP, InterWorx can reinstall it for you. If port 53 is not responding on your system, and the firewall is configured to let traffic through to that port, it is good to check that a DNS Service is installed on that IP. If traffic is being let through on your InterWorx server on the default DNS port of 53, but it not responding to DNS queries, it is possible that there is no DNS service installed on that IP.
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