96 lines
5.2 KiB
Text
96 lines
5.2 KiB
Text
The following the list of error messages that dnswalk will
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return if it sees a potential problem with the database.
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Duplicate messages will be suppressed automatically for each
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zone.
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X PTR Y: unknown host
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X is a PTR record to Y, but Y is not a valid host (no A
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record). These are often left over from when someone
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deleted a host from the DNS and forgot to delete the
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PTR record. These records should be removed.
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X PTR Y: A record not found
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X is a PTR record to Y, but the IP address associated
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with the PTR record is not listed as an address for Y.
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There should be an A record for every valid IP address
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for a host. Many Internet services will not talk to
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you if you have mismatched PTR records.
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X PTR Y: CNAME (to Z)
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X is a PTR record to Y, but Y is a CNAME to Z. PTR
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records should point to the real name of a host, not an
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alias.
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X CNAME Y: unknown host
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X is aliased to Y, but Y is not a valid host (no A
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record). This is a stale entry and should be removed.
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X CNAME Y: CNAME (to Z)
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X is aliased to Y, but Y is aliased to Z. CNAMEs
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should not be chained together. It has been known to
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cause problems with some software.
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X MX Y: unknown host
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X is an MX to Y, but Y is not a valid host (no A
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record). This is a stale entry and should be removed.
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X MX Y: CNAME (to Z)
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X is an MX to Y, but Y is an alias for Z. MX records
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must point to the canonical name, not an alias.
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X A Y: no PTR record
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X has an IP address Y, but there is no PTR record to
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map the IP address Y back to a hostname (usually X).
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Many Internet servers (such as anonymous FTP servers)
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will not talk to addresses that don't have PTR records.
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warning: X has only one authoritative nameserver
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Zones should have more than one authoritative name-
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server, in case one is down or unreachable. Preferably
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one should be off-site. Make sure the parent and child
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nameservers list all authoritative nameservers for a
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zone in the NS list.
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X: invalid character(s) in name
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Allowable characters in a domain name are the ASCII
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letters a through Z the digits 0 through 9, and the "-"
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character. A "." may be used only as a domain separa-
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tor. Using non-standard characters can cause unexpected
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software problems.
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X: domain occurred twice, forgot trailing '.'?
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A sanity check which looks for "dom.ain.dom.ain." in a
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name. This is often caused by forgetting to put a
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trailing '.' on the end of a name.
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X A Y: points to Z
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X has Y for an IP address, but the PTR record associ-
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ated with Y returns "Z" as the name associated with
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that host. This is not necessarily an error (for exam-
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ple if you have an A record for your domain name), but
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may be an indication of an A record which points to the
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wrong host, or a PTR record that points to the wrong
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host. You will get this error if you are trying to
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alias one host to another with an A record. You should
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use a CNAME instead.
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X NS Y: lame NS delegation
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Y is a listed nameserver for zone X, but Y is not
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returning authoritative data for zone X. This is usu-
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ally the result of a lack of communication on the part
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of the respective hostmasters. Lame delegations are
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not fatal problems except in severe cases, they just
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tend to create significant increases in DNS traffic.
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NS records for the parent and child domains should be
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consistent, and each server listed in the NS record
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MUST be able to answer with authoritative data, by
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being explicitly configured as a primary or secondary
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for the zone.
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X NS Y: nameserver error (lame?)
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These are any errors returned while contacting other
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nameservers (like connection refused or timeout) This
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could mean a lame delegation (the host is not running
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a nameserver or is misconfigured), or simply that the
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nameserver is temporarily unreachable.
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Cannot check X: no available nameservers!
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The X zone was delegated with NS records but all the
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nameservers for the zone are either unavailable or say
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that they have no data for the zone (are lame). Verify
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that the X zone isn't a typo, and if not make sure that
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all the listed nameservers are configured to answer
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with data for the zone.
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SEE ALSO
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RFC 1034 - "DOMAIN NAMES - CONCEPTS AND FACILITIES"
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RFC 1035 - "DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION"
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RFC 1123 - "Requirements for Internet Hosts -- Application and Support"
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Paul Albitz, Cricket Liu: "DNS and BIND" O'Reilly & Associates.
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RFC 1912 - "Common DNS Operational and Configuration Errors"
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http://www.dns.net/dnsrd/ - DNS Resources Directory
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