there is a slight delat in ping reply
in [Linux Networking]
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From: d on 31 Jul 2006 10:15 I have a DELL 2650 installed with FC5. After setting up the network I executed some ping test to test the connections. Within the LAN the ping replies are as expected. However, when I ping servers outside the LAN I've noticed a slight delay in the reply of what I think is the DNS lookup. After that the replies are as expected. Example: linux% ping cnet.com PING cnet.com (216.239.113.101) 56(84) bytes of data. (*** here is where the delay is; about 2 seconds or so ***) 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): icmp_seq=1 ttl=247 time=102 ms 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): icmp_seq=2 ttl=247 time=85.7 ms 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): icmp_seq=3 ttl=247 time=93.3 ms 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): icmp_seq=4 ttl=247 time=241 ms 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): icmp_seq=5 ttl=247 time=92.6 ms All the above replies are as expected. I can't put my figure on the problem. I've checked my /etc/resolv.conf. It looks OK. Contains only the COMCAST DNS IP addresses and that's it. I have another Linux server of RH9 flavor and I don't see this problem.
From: Ken Roberts on 31 Jul 2006 10:18 d wrote: > I have a DELL 2650 installed with FC5. After setting up the network I > executed some ping test to test the connections. Within the LAN the > ping replies are as expected. However, when I ping servers outside the > LAN I've noticed a slight delay in the reply of what I think is the DNS > lookup. After that the replies are as expected. Example: > > linux% ping cnet.com > PING cnet.com (216.239.113.101) 56(84) bytes of data. > (*** here is where the delay is; about 2 seconds or so ***) > > 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): > icmp_seq=1 ttl=247 time=102 ms > 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): > icmp_seq=2 ttl=247 time=85.7 ms > 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): > icmp_seq=3 ttl=247 time=93.3 ms > 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): > icmp_seq=4 ttl=247 time=241 ms > 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): > icmp_seq=5 ttl=247 time=92.6 ms > > All the above replies are as expected. I can't put my figure on the > problem. I've checked my /etc/resolv.conf. It looks OK. Contains only > the COMCAST DNS IP addresses and that's it. I have another Linux > server of RH9 flavor and I don't see this problem. So do a "host cnet.com" and then ping by IP address to see if the delay still exists. Also, does cancelling the ping and then immediately restarting it still give you the delay?
From: Allen McIntosh on 31 Jul 2006 10:38 Ken Roberts wrote: > d wrote: >> However, when I ping servers outside the >> LAN I've noticed a slight delay in the reply of what I think is the DNS >> lookup. After that the replies are as expected. Example: >> >> linux% ping cnet.com >> PING cnet.com (216.239.113.101) 56(84) bytes of data. >> (*** here is where the delay is; about 2 seconds or so ***) >> >> 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): >> icmp_seq=1 ttl=247 time=102 ms > So do a "host cnet.com" and then ping by IP address to see if the delay > still exists. > > Also, does cancelling the ping and then immediately restarting it still > give you the delay? See if the delay goes away when you use ping -n
From: d on 31 Jul 2006 17:56 Allen McIntosh wrote: > Ken Roberts wrote: > > d wrote: > > >> However, when I ping servers outside the > >> LAN I've noticed a slight delay in the reply of what I think is the DNS > >> lookup. After that the replies are as expected. Example: > >> > >> linux% ping cnet.com > >> PING cnet.com (216.239.113.101) 56(84) bytes of data. > >> (*** here is where the delay is; about 2 seconds or so ***) > >> > >> 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): > >> icmp_seq=1 ttl=247 time=102 ms > > So do a "host cnet.com" and then ping by IP address to see if the delay > > still exists. > > > > Also, does cancelling the ping and then immediately restarting it still > > give you the delay? > > See if the delay goes away when you use ping -n Results: - ping IP (fast reply no delays) - ping -n IP (fast reply no delays) - ping hostname (2-3 second delay) - ping -n hostname (2-3 second delay) - host hostname (seems normal) - dig hostname (seems nornal)
From: d on 31 Jul 2006 18:43
d wrote: > Allen McIntosh wrote: > > Ken Roberts wrote: > > > d wrote: > > > > >> However, when I ping servers outside the > > >> LAN I've noticed a slight delay in the reply of what I think is the DNS > > >> lookup. After that the replies are as expected. Example: > > >> > > >> linux% ping cnet.com > > >> PING cnet.com (216.239.113.101) 56(84) bytes of data. > > >> (*** here is where the delay is; about 2 seconds or so ***) > > >> > > >> 64 bytes from c17-sha-redirect-lb.cnet.com (216.239.113.101): > > >> icmp_seq=1 ttl=247 time=102 ms > > > So do a "host cnet.com" and then ping by IP address to see if the delay > > > still exists. > > > > > > Also, does cancelling the ping and then immediately restarting it still > > > give you the delay? > > > > See if the delay goes away when you use ping -n > > Results: > - ping IP (fast reply no delays) > - ping -n IP (fast reply no delays) > - ping hostname (2-3 second delay) > - ping -n hostname (2-3 second delay) > - host hostname (seems normal) > - dig hostname (seems nornal) Its more like a 4-5 second delay after I hit the RETURN key and before the replies starting coming to the screen. This is strange. on't know what to make of it. |