Hello,
I have been testing xen for a few days now, and things seem to be working
almost fine.
However, I am having seriously annoying problems with my networking setup.
On both dom0 and any domU I don’t seem to be able to resolve hostnames.  I
know it is definitely caused by xen and not some other networking related
issue as if I disable xend on bootup, nslookup resolutions and pings to
hosts lookup fine.
I can ping to ip addresses fine both locally and on the internet fine, just
not resolve hostnames.  
My ifconfig output on dom0 gives the following:
eth0      Link encap:Ethernet  HWaddr 00:E0:18:B5:96:2E  
          inet addr:192.168.1.50  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::2e0:18ff:feb5:962e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:13 errors:0 dropped:0 overruns:0 frame:0
          TX packets:15 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1084 (1.0 KiB)  TX bytes:1118 (1.0 KiB)
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:560 (560.0 b)  TX bytes:560 (560.0 b)
peth0     Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:133 errors:0 dropped:0 overruns:0 frame:0
          TX packets:135 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:18299 (17.8 KiB)  TX bytes:14960 (14.6 KiB)
          Interrupt:18 
vif0.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
          inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:15 errors:0 dropped:0 overruns:0 frame:0
          TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1118 (1.0 KiB)  TX bytes:1470 (1.4 KiB)
xenbr0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF  
          inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:524 (524.0 b)  TX bytes:468 (468.0 b)
And if I enable virtual domains vif1.0 enables fine.  I also have the bridge
setup correctly I believe through:
bridge name     bridge id               STP enabled     interfaces
xenbr0          8000.feffffffffff       no              peth0
                                                        vif0.0
iptables is running with the following:
Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         
RH-Firewall-1-INPUT  all  --  anywhere             anywhere            
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
RH-Firewall-1-INPUT  all  --  anywhere             anywhere            
Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
Chain RH-Firewall-1-INPUT (2 references)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     icmp --  anywhere             anywhere            icmp any 
ACCEPT     ipv6-crypt--  anywhere             anywhere            
ACCEPT     ipv6-auth--  anywhere             anywhere            
ACCEPT     udp  --  anywhere             224.0.0.251         udp dpt:5353 
ACCEPT     udp  --  anywhere             anywhere            udp dpt:ipp 
ACCEPT     all  --  anywhere             anywhere            state
RELATED,ESTABLISHED 
ACCEPT     tcp  --  anywhere             anywhere            state NEW tcp
dpt:ssh 
REJECT     all  --  anywhere             anywhere            reject-with
icmp-host-prohibited
As I say, pings are fine, just network name resolutions.  I have tried using
ethtool to do the following:
ethtool -K peth0 tx off
as suggested by one other member on the mailing list but this didn't work
either.
I am at the end of the line in terms of ideas - it seems such a
frustratingly annoying problem and I believe I am so close!
Any help very much appreciated!
Nick