DNS question

[Bill H.]

Have a couple of XP computers networked.

Had AT&T come out to "fix" a modem problem. Now, they can't get the
networked printers to work.

Looked at ipconfig on the two PCs (also have macs and they, too, can no
longer print to the networked printer). (For the macs, I think the printer
was set up using the shared printer on one of the PCs, but I'm not entirely
sure on that.)

Computer 1 and 2 had almost the same entries, so I'm wondering if the
differing entry could be a source of the problem.

Their IP addresses are 192.168.1.100 and .101

Both have the same subnet mask (255.255.255.0), and default gateway and dhcp
server (192.168.1.254)

However, the .101 computer has 192.168.1.254 as the DNS server, but computer
100 had two listings for DNS: 68.94.156.1 and 68.94.157.1.

Both can see the internet just fine, but cannot PING each other (though both
can ping the modem/router at 192.168.1.254).

Could the different DNS listings be a source of the problem?

Thanks.

 

[Lem]

Have a couple of XP computers networked.

Had AT&T come out to "fix" a modem problem. Now, they can't get the
networked printers to work.

Looked at ipconfig on the two PCs (also have macs and they, too, can no
longer print to the networked printer). (For the macs, I think the printer
was set up using the shared printer on one of the PCs, but I'm not entirely
sure on that.)

Computer 1 and 2 had almost the same entries, so I'm wondering if the
differing entry could be a source of the problem.

Their IP addresses are 192.168.1.100 and .101

Both have the same subnet mask (255.255.255.0), and default gateway and dhcp
server (192.168.1.254)

However, the .101 computer has 192.168.1.254 as the DNS server, but computer
100 had two listings for DNS: 68.94.156.1 and 68.94.157.1.

Both can see the internet just fine, but cannot PING each other (though both
can ping the modem/router at 192.168.1.254).

Could the different DNS listings be a source of the problem?

Thanks.

Short answer: no.

Longer answer:
This sounds like a firewall setting on one or both of the computers. If
you are not using the Windows firewall, make sure that LAN traffic (e.g.
192.168.1.0 - 192.168.1.255) is allowed. Note that an antivirus
application's "Internet Worm Protection" or the like actually is a
firewall that needs to be configured.

Computers on the same subnet should be able to communicate with each
other, specifically, one should be able to Ping the other. With a
subnet mask of 255.255.255.0 (typical for home routers), this means that
the first 3 octets of the IP addresses should be the same. In your case,
they are: 192.168.1.100 and 192.168.1.101 (the first 3 octets are
192.168.1).

If you Ping using IP addresses, DNS never comes into play. DNS is a
method of translating domain names (e.g., google.com) into IP addresses
(e.g., 74.125.53.100). In home Internet connections, the ISP provides
one or two DNS servers. If you use a router, the router forwards the
address(es) of the ISP's DNS servers to the LAN clients *if* the client
is set to obtain an DNS server address automatically. If the LAN clients
are instead set to use the router's IP as the DNS server, the router
should just pass DNS requests on the the ISP's DNS server.

On the computer where you see 192.168.1.254 (which is your router) as
the DNS server, check the TCP/IP properties and ensure that the radio
button to "Obtain a DNS address automatically" is selected.

 

[Bill H.]

Thanks, Lem.

That's along the same lines I was thinking, except all was working before
the tech visit. But, an automatic update may have affected the ability of
the computers to see each other.

Pinging the router was to show that each could see the router yet not see
each other. I'll have to check on firewalls, etc. I think they are using
windows firewall and mcafee antivirus.

--Bill

 

[FiOS Dave]

Thanks, Lem.

That's along the same lines I was thinking, except all was working before
the tech visit. But, an automatic update may have affected the ability of
the computers to see each other.

Pinging the router was to show that each could see the router yet not see
each other. I'll have to check on firewalls, etc. I think they are using
windows firewall and mcafee antivirus.

--Bill

Hi Bill,

If you recently had FiOS installed for TV, their boxes use addresses .100
and up,
so that could be a problem. Also, if you DON'T let DHCP handle an address,
and enter one manually, I've noticed that can cause a similar problem.
Make sure that DHCP is handling the addresses.

Dave