Cannot reach certain domains via TCP/IP ?!

[spacemuis]

Hi,
For the last few days I've been having a weird problem on my Win7/64 laptop: I cannot reach certain domains/public IP subnets.
Examples: intellicast.com, cnn.com, and others.
At a command prompt I can do an nslookup on those domains, no problem.
But if I try ping or tracert I consistently get back a message "General failure" for those domains.
I've tried googling to no avail.
I don't have 3rd party security s/w installed - only the standard Win7 firewall and Microsoft Security Essentials.
I thought there might be a weird static route in my TCP/IP setup, but can't see anything weird - here's my route setup.

[SIZE="2"]Interface List
 20...00 24 d7 3d 9d 99 ......Microsoft Virtual WiFi Miniport Adapter
 13...00 24 d7 3d 9d 98 ......Intel(R) Centrino(R) Ultimate-N 6300 AGN
 11...d8 d3 85 39 d0 02 ......Intel(R) 82577LM Gigabit Network Connection
  1...........................Software Loopback Interface 1
 19...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
 17...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3
 16...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
 18...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #4
===========================================================================

IPv4 Route Table
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0    192.168.1.254    192.168.1.102     20
        127.0.0.0        255.0.0.0         On-link         127.0.0.1    306
        127.0.0.1  255.255.255.255         On-link         127.0.0.1    306
  127.255.255.255  255.255.255.255         On-link         127.0.0.1    306
      192.168.1.0    255.255.255.0         On-link     192.168.1.102    276
    192.168.1.102  255.255.255.255         On-link     192.168.1.102    276
    192.168.1.255  255.255.255.255         On-link     192.168.1.102    276
        224.0.0.0        240.0.0.0         On-link         127.0.0.1    306
        224.0.0.0        240.0.0.0         On-link     192.168.1.102    276
  255.255.255.255  255.255.255.255         On-link         127.0.0.1    306
  255.255.255.255  255.255.255.255         On-link     192.168.1.102    276
===========================================================================
Persistent Routes:
  Network Address          Netmask  Gateway Address  Metric
       172.24.1.0    255.255.255.0       172.24.4.5       1
===========================================================================

IPv6 Route Table
===========================================================================
Active Routes:
 If Metric Network Destination      Gateway
 16     58 ::/0                     On-link
  1    306 ::1/128                  On-link
 16     58 2001::/32                On-link
 16    306 2001:0:4137:9e76:2886:375f:d67b:38cc/128
                                    On-link
 11    276 fe80::/64                On-link
 16    306 fe80::/64                On-link
 16    306 fe80::2886:375f:d67b:38cc/128
                                    On-link
 11    276 fe80::bc79:59cf:3485:4ff3/128
                                    On-link
  1    306 ff00::/8                 On-link
 16    306 ff00::/8                 On-link
 11    276 ff00::/8                 On-link
===========================================================================
Persistent Routes:
  None[/SIZE]

That one IPv4 persisten route is for a client's network.

Then I thought it might be something in my router (the default gateway 192.168.1.254 you see there) - but from other computers I can browse to and ping those domains, so the problem lies with my own PC.
Restarting Windows hasn't helped - it's persistent.

The affected domains don't seem to have anything in common, e.g. fall within a recognisable IP range, e.g. intellicast.com [216.236.239.10] and cnn.com [157.166.255.18] are nowhere near each other.

I just tried a test - switched off my Win7 firewall on this my "Home" network, but could still not ping those domains.

It hasn't been a major problem because I can still reach all the important sites I need to, but this has got me puzzled and needs fixing.

My best bet is that the routing table is corrupted ... can anyone interpret the routing info shown above and tell me why I can't route to the two example IP addresses listed above??

Any other ideas and/or suggestions?
Your help is appreciated

 

[ponder]

But if I try ping or tracert I consistently get back a message "General failure" for those domains.

Just want to clarify, are you using the domain names for ping/traceroute or the IP addresses?
What happens if you use the IP addresses for ping/traceroute?
What are the IP's of your DNS servers (on the PC & router)?

 

[noswal]

reboot router and see if problem persists

 

[syntax]

Just want to clarify, are you using the domain names for ping/traceroute or the IP addresses?
What happens if you use the IP addresses for ping/traceroute?
What are the IP's of your DNS servers (on the PC & router)?

yeah, its almost certainly a dns issue here.
use google dns and see what happens (8.8.8.8), you may even be resolving the ip's incorrectly in the first place

 

[spacemuis]

Thanks for the feedback. I did mention that the DNS lookup succeeds (ok, I did say NSLOOKUP works, but you know what I mean).
The problem persists with those specific domains whether I ping/tracert them with the domain name or via their IP address, that's why I think it's a routing problem of some sort.
I did a quick test using nslookup to 8.8.8.8 and it gave me the same IP address for intellicast.com (216.236.239.10) as my default DNS - which is my router (192.168.1.254) which relays the request to the standard MWEB DNS servers.

UPDATE: Just figured out what the problem is - I'll post solution here in case anybody else is as dumb as I am in future: I noticed while restarting a popup window from Peerblock updating itself. Now i must have installed this thing many months ago and when I checked now I discovered that it was blocking HTTP traffic also to "suspect" domains... so either the peerblock blacklist has been muddied recently (by inclusion of even CNN.COM!) to the point of making it useless, or the HTTP blocking got switched on somehow (not by me!).
Anyway, I never wanted this to block HTTP traffic anyway, so turning off that flag has restored full internet access via browser.

 

[syntax]

Thanks for the feedback. I did mention that the DNS lookup succeeds (ok, I did say NSLOOKUP works, but you know what I mean).
The problem persists with those specific domains whether I ping/tracert them with the domain name or via their IP address, that's why I think it's a routing problem of some sort.
I did a quick test using nslookup to 8.8.8.8 and it gave me the same IP address for intellicast.com (216.236.239.10) as my default DNS - which is my router (192.168.1.254) which relays the request to the standard MWEB DNS servers.

UPDATE: Just figured out what the problem is - I'll post solution here in case anybody else is as dumb as I am in future: I noticed while restarting a popup window from Peerblock updating itself. Now i must have installed this thing many months ago and when I checked now I discovered that it was blocking HTTP traffic also to "suspect" domains... so either the peerblock blacklist has been muddied recently (by inclusion of even CNN.COM!) to the point of making it useless, or the HTTP blocking got switched on somehow (not by me!).
Anyway, I never wanted this to block HTTP traffic anyway, so turning off that flag has restored full internet access via browser.

It must have been blocking more than just http traffic if your pings were also failing.

 

[spacemuis]

It must have been blocking more than just http traffic if your pings were also failing.

You are quite right, sir. With HTTP blocking turned off I still cannot ping those sites - ping only succeeds if I disable peerblock entirely.
Well I don't really care to be able to ping most sites, but I will keep this in mind if I experience any other, non-http problems e.g. streaming.