Our email group have been complaining about a issue of email sent by certain users bouncing and I started debugging and found out that those users are using email-servers in subnet1. Emails sent out by users in subnet2 were OK.
The email-client-hosts use dns-recursive-resolvers depending on their location. The names being queried by email-client-hosts are external names (not in our named config) and our recursive resolvers recurse and gets response to these queries as expected. Summary of my investigation: ============================ # dns-recursive-resolver1 is in subnet1 # I execute this on dns-recursive-resolver1 and the query times out dig @other-auth-nameserver name1.com. A # TIMEOUT dig @other-auth-nameserver name1.com. MX # TIMEOUT # dns-recursive-resolver2 is in subnet2 # I execute the following dig command on dns-recursive-resolver2 and it returns response (A record) as # expected. dig @other-auth-nameserver name1.com. A # OK - responds correctly dig @other-auth-nameserver name1.com. MX # OK - responds correctly I spoke to the sysadmin who maintains 'other-auth-nameserver' and he responded that they are NOT 'black-hole'ing or 'bogus'ing subnet1 in named.conf on 'other-auth-nameserver'. Also, they don't have any network ACL or firewall config to block DNS queries from subnet1. Question: What else should I be looking? _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
