Does DNS UDP Port 53 need to be open for IE to work via ics on the client PC?

[Allen Nelson]

I have two pc's networked as follows: pc1 has two ethernet cards; one
connects to a dsl interface device; the second nic is a peer-to-peer
(tcp/ip) connection
to a hub. Pc2's nic is a peer-to-peer (tcp/ip) connection to the same hub
that pc1
is connected. I have the SP2 Win Firewall turned on. Ics is turned on for
the dsl
connection, but file and print sharing is turned off. Pc2 has file and print
sharing tuned on.

If I open udp port 53 (dns), all works fine for pc2. I can share the
internet connection, but if I
turn 53 off, the ics stops working. When I look at pc1's security log for
dropped packets, it shows all packets are dropped from pc2. I do not
understand
why port 53 should be open for ics to work. Could someone explain. Thanks!

 

[Doug Sherman [MVP]]

PC1 is acting as a DNS proxy server for PC2, so it must have an open port
(53) for DNS queries.

Doug Sherman
MCSE Win2k/NT4.0, MCSA, MCP+I, MVP

 

[Allen Nelson]

Thanks for the response. How do I get it to use the isp for dns?

 

[Doug Sherman [MVP]]

You can manually configure the ICS client machine:

IP address = 192.168.02
Gateway = 192.168.0.1
Prim DNS = IP address of ISP's DNS server.

In this case you should not need to open port 53 on the ICS host.

Doug Sherman
MCSE Win2k/NT4.0, MCSA, MCP+I, MVP

 

[Allen Nelson]

Thanks for the great information and help!