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Usually after $TTL and $ORIGIN there is a line starting with @ and IN in zone name then email address of admin, what does @ mean here and in the next entries?

Radu Rădeanu
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Hojat Taheri
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1 Answers1

11

$ORIGIN is used in two contexts during zone file processing:

  1. The symbol @ forces substitution of the current (or synthesized) value of $ORIGIN. The @ symbol is replaced with the current value of $ORIGIN.
  2. The current value of $ORIGIN is added to any 'unqualified' name (any name which does not end in a 'dot').

Example of @ symbol replacement:

; example.com zone file fragment 
; no $ORIGIN present and is synthesized from the 
; zone name in named.conf
....
@          IN      NS     ns1.example.com. 
; ns1.example.com is the name server for example.com
....
$ORIGIN uk.example.com.
@          IN      NS     ns2.example.com. 
; functionally identical to
; uk.example.com. IN NS ns2.example.com.
; ns2.example.com is the name server for uk.example.com
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Radu Rădeanu
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    if `$ORIGIN` is missing then `@` refers to the [name of the zone](https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/networking_guide/sec-bind). – Bob Stein Aug 17 '18 at 17:07