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41 How to determine BIND query rates (qps)

Question: How can I find out what query rate my BIND nameserver is handling? Answer: This answer is incomplete There are other ways of determining the QPS of a server. This answer provides guidance for the one that is expected to be applicable to the most…

42 Why is BIND logging "adb: grow_entries to <number>" and "adb: grow_names to <number>"?

Question: Since installing a new version of BIND, I'm getting the following informational messages on starting named. What do they mean? 18-Nov-2011 03:35:14.872 database: info: adb: grow_entries to 1531 starting 18-Nov-2011 03:35:14.874 database: info: adb:…

43 What does 'BITWS' mean?

Question: In BIND 9.9.0 pre-release versions I'm seeing the serial number for my dynamic zone being reported by named-journalprint as BITWS=2011111502. What does BITWS mean? Answer: What is being reported by journalprint is the serial number of the unsigned…

44 DNS Cache snooping - should I be concerned?

DNS cache snooping is a technique that can be employed for different purposes by those seeking to benefit from knowledge of what queries have been made of a recursive DNS server by its clients. Uses of this information vary, ranging from planning which mis-typed…

45 Background info about 'maximum number of FD events' log messages

Log messages reading maximum number of FD events received mean that when checking to see whether any sockets were ready to be read from, named found that there were more than 64 of them. These log messages are not related to the maximum number of open file…

46 How does clients-per-query work?

Question: How does clients-per-query work when named is running? There is often confusion over clients-per-query, especially when encountering logfile entries such as these below: 10-May-2011 13:01:02.745 resolver: notice: clients-per-query increased to 20…

47 Considerations when choosing and configuring Load Balancers

Question: What sort of features and functionality should be borne in mind when choosing and configuring a Load Balancer, either to spread the load of recursive queries between a number of recursive servers, or to provide authoritative DNS replies based on…

48 Defining a named.conf ACL for 'any IPv6' address

Question: Is there a built-in ACL for named.conf that is for any IPv6 address? Answer: The following ACL definitions are for all IPv6 and all IPv4 addresses respectively: acl any6 { ::0/0; }; acl any4 { 0.0.0.0/0; };

49 What does "isc_socket_create: fcntl//rreserved: Too many open files" mean?

Question: What do these named errors signify - and how should they be investigated? 10-May-2011 15:41:13.815 general: error: isc_socket_create: fcntl/reserved: Too many open files 10-May-2011 15:41:13.815 general: error: isc_socket_create: fcntl/reserved:…

50 Why does rndc reconfig sometimes resolve recursive server problems with some domains?

There are many poorly-configured DNS servers that provide records that break the the DNS protocols. Depending on how poorly these servers comply, name resolution may work most of the the time. Factors influencing this include the relative TTLs of parent and…