Connectivity

[Mark_Andrews at isc.org]

> At the risk of sounding stupid, If a firewall disables pinging will this effe
> ct
> dns.

	No.  That is to say they are it is blocking ICMP ECHO
	request.  If it blocks all ICMP messages then there is the
	potential to slowdown and potentially break the DNS.

> How does dns reachout and touch , lets say a forwarder?

	The same way any DNS query is made.  It sends a UDP DNS
	query to port 53 on the forwarder, the answer then comes
	back from this port.  Most firewalls don't let random UDP
	traffic through.  Often you need to force the queries to
	be made from specific ports.  With BIND 8 this is controlled
	by the query-source option.

	Mark

> 
> Stating to feel useless 8-)
> ----
> This mail item has passed through an insecure network. 
> All enquiries should be directed to the message author.
> 
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org