We have a few IIS web servers (all in same subnet/VLAN)
that are load-balanced using NLB.
Users at a remote office (of only 3 PCs) have been complaining of
frequent slowness in loading a web page: not even doing data query
but simply upon login to the main menu page (ie doesn't involve
DB servers yet).
These 3 users would access a url of the NLB & when this happens,
we tried accessing from the users' PCs different web servers'
url directly (to bypass the NLB) & could reproduce this problem:
2 of the web servers are slow to load the main page (25-39 secs)
while the rest of the web servers would load the same main
menu page within 1 sec.
I installed httpwatch basic edition on one of the user's PC to test out.
Attachment 1 is the screen showing web007's fast loading time.
Attachment 2 is the screen showing web010's slow loading time.
occasionally the web010 would load within 2 secs but at most
times, it would take 25-39 secs.
To isolate out the DNS, I've hardcoded web010 & web007's IP address on
that user PC's c:\windows\system32\driver
s but web010 still
takes as long to send back the mainmenu.aspx.
During this testing, I issued 'pathping -q 10 IP_addr_of the web servers'
& they all returned back with good timings of less than 3 secs for every
During these slow loading times, the CPU/RAM utilization of all the web
servers are less than 20%. Also users from other remote locations
could load very fast the very same web010 page. I also tried using the
user's PC to load a .js file (from web010) that's about 15 times larger
than mainmenu.aspx & it loads in less than 1 sec.
Someone in EE suggested this could be an MTU issue but I've checked
the "show int xxx" outputs of the Cisco ports of the 3 PCs as well as
the Cisco ports that the web servers are all connected: the counter/
column for "Giants" is 0 (so I suppose this means no MTU issue at
both the servers & PCs ends).
When web010's page was consistently slow to load, if I entered web010's
IP addr in the IE browser to load the same url, it loads within 1 sec
consistently. Strange that when I define/hardcode web010's IP in the PC's
hosts table (& I verified the hosts' table entry takes effect by intentionally
entering an unused IP & did a ping), it loads slow (25-39secs): so I really
can't conclude if this is a DNS issue.
I've seen one case when pinging web010 on this PC, it resolves to one
IP addr & the next minute, it resolves to a different IP addr. However,
ipconfig/all on the PC showed the DNS used is still the same.
How else can I troubleshoot this further?
Would the Event Viewer logs in the DNS server help? If so, I'll ask the
DNS admin to provide