diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml index 1ddb958b13..6fab1ba6c8 100644 --- a/doc/arm/Bv9ARM-book.xml +++ b/doc/arm/Bv9ARM-book.xml @@ -18,7 +18,7 @@ - PERFORMANCE OF THIS SOFTWARE. --> - + BIND 9 Administrator Reference Manual @@ -8052,7 +8052,7 @@ avoid-v6-udp-ports { 40000; range 50000 60000; }; Sets the advertised EDNS UDP buffer size in bytes to control the size of packets received. - Valid values are 512 to 4096 (values outside this range + Valid values are 1024 to 4096 (values outside this range will be silently adjusted). The default value is 4096. The usual reason for setting edns-udp-size to a non-default @@ -8060,24 +8060,36 @@ avoid-v6-udp-ports { 40000; range 50000 60000; }; firewalls that block fragmented packets and/or block UDP packets that are greater than 512 bytes. + + named will fallback to using 512 bytes + if it get a series of timeout at the initial value. 512 + bytes is not being offered to encourge sites to fix their + firewalls. Small EDNS UDP sizes will results in the + excessive use of TCP. + max-udp-size - - - Sets the maximum EDNS UDP message size named will - send in bytes. Valid values are 512 to 4096 (values outside - this range will be silently adjusted). The default + + + Sets the maximum EDNS UDP message size + named will send in bytes. + Valid values are 512 to 4096 (values outside this + range will be silently adjusted). The default value is 4096. The usual reason for setting - max-udp-size to a non-default value is to get UDP - answers to pass through broken firewalls that - block fragmented packets and/or block UDP packets - that are greater than 512 bytes. + max-udp-size to a non-default + value is to get UDP answers to pass through broken + firewalls that block fragmented packets and/or + block UDP packets that are greater than 512 bytes. This is independent of the advertised receive buffer (edns-udp-size). + + Setting this to a low value will encourge additional + TCP traffic to the nameserver. + @@ -15183,6 +15195,7 @@ zone "example.com" { +