Router can ping by IP/domain, LAN (NAT) Client Can only ping by IP

[T_K]

I am having difficulty determining where my, apparent, DNS issue is occurring.  The 4331 is able to ping 8.8.8.8, and is able to ping www.google.com, but my LAN Client can only ping 8.8.8.8, LAN Client attempts to ping www.google.com indicate that the host cannot be found (Windows 10 Client with static DNS server 8.8.8.8 assigned, connected directly to 4331's GE 0/0/1 interface, Client performs as expected when connected directly to ISP GW and assigned the 4331's static IP address).  The 4331's configuration is, with some differences due to interface numbering and OS versions, the same as the 2851's that I am replacing (ACLs, IP Address, SM, GW of last resort, etc.)  My hope is that someone here will notice something that I have missed/am missing, or have some guidance on how to investigate this more efficiently than I have been able (over the past few days).  I have attached a sanitized copy of the 4331's configuration to this post.  Thank you for any assistance that you are able provide.

[T_K]

It may work when, I put it into production, using the production DNS servers but my question remains what is preventing my client machine from utilizing 8.8.8.8 as a DNS server when it is connected to the 4331's LAN.  I do not see anything obvious, in the configuration, that would account for this but I can only beleive that something is preventing the dns queries from getting out to the internet or is preventing them from getting back in.

[balaji.bandi]

It may work when, I put it into production, using the production DNS servers but my question remains what is preventing my client machine from utilizing 8.8.8.8 as a DNS server when it is connected to the 4331's LAN.

this question needs to ask yourself, how does your network connection connect? and you are not providing enough information here on your network, the diagram you provided what you looking to do cut over.

I have asked some questions - let me type again for more clarity :

That is correct, on the configuration that I posted, it lists the DNS servers that will be utilized by the client machines in the production network

if this works in an exciting environment, when you do cut over that should work as expected.  

OP -  2851's that I am replacing (ACLs, IP Address, SM, GW of last resort, etc.)   - So that is the conclusion.

On your picture for now instead of 4431 you have 2851 (if the client using same DNS working, when you replace that should work).

[T_K]

I understand why you would think that but moving the 4331, with the posted config, into the 2851's place, prevents the client from using 8.8.8.8 for dns; this is not due to the DHCP configuration as the 8.8.8.8 is statically set on the client.

[MHM Cisco World]

Yes Sure I am totally with you, 
the client must use external DNS server not router as DNS proxy. 
the issue is 
when we change the DNS to be 8.8.8.8
still the client use specific DNS server, that what need more investigate.

if you can make dns server 8.8.8.8 (under dhcp) but this time reboot the client PC. 
 

[T_K]

I am not sure I understand, when we set the DHCP pool's dns server value to 8.8.8.8, earlier today, the client machine reflected the change after the release and renewal of its dhcp assignment.  

[MHM Cisco World]

Yes but are OS use correct DNS ?
we see after do this step still OS of client suing private DNS server not public 8.8.8.8

[T_K]

Yes, the OS is configured to use 8.8.8.8 for DNS but there does not appear to be dns resolution regardless of if 8.8.8.8 is set statically or by dhcp.

[MHM Cisco World]

In Windows, this suffix is used to:

1. be automatically added to any DNS queries that do not specify a domain name. Ex: when you try to access a website by only specifying its hostname, such as www. It will automatically add the suffix domain specified by the DHCP (or GPO) administrator of your network to this query, turning it into the FQDN www.domainsuffixspecified.com.

2. dynamically register the hostname of your workstation within the local network's DNS servers, turning your device into a 'member' of this network. Example: your computer is named mypc-01, but when it receives a DNS suffix from the DHCP (or, again, via GPO), it will be internally recognized as mypc-01.thedomainsuffixspecified.com.

from Yesterday I check and check the only thing make DNS failed is the domain name add or replace by router or OS 

can you ping   

ping google.com 

[T_K]

Thank you for the information, but I must admit I do not undertand how it applies to the issue I am experiencing.  Regardless, I have reloaded the config, from the original post, changed the DHCL pool's dns-server to 8.8.8.8, and restarted the client machine; the client machine is unable to ping google.com, ping request could not find host google.com .

[MHM Cisco World]

 domain-name <RemovedA>.com <<- remove this for try NOW only 

 please do above and restart PC, and do ping google.com

[T_K]

I have removed the domain-name from the DHCP pool.  I am still unable to ping by names google.com or www.google.com ; ping request could not find host for both requests.

[balaji.bandi]

trying to catch up on things -

Clarify below things : (which was asked below - looks like you are more stressing your problem than giving us more information to understand the issue here)  - Do one thing at a time what suggested, and post your results in a step by step for us to understand give you right direction.

1. when you do testing, is the old router and new router co-exist simultaneously in the network ?

2. how does your network looks like ? is the both the router do in same ISP router ? (show in diagram)

3. can you also post your OLD Router config - when it Live ?  - is the laptop with DNS 8.8.8.8 works on that router (provide evidence of testing)

Note DNS Security is Hole biggest risk in the ISP DSL world, so some providers don't like using google DNS or any other DNS due to some reason - for your guidance this.

I understand why you would think that but moving the 4331, with the posted config, into the 2851's place, prevents the client from using 8.8.8.8 for dns; this is not due to the DHCP configuration as the 8.8.8.8 is statically set on the client.

We don't know if we need to troubleshoot to understand the issue (some time simple - we may be missing something here).

[T_K]

Good day and my apologies if any curtness is perceived in this response, I am mobile today but didn't want you to think I was ignoring your response:

I did rephrase the question as it appeared what I was investigating was not being interpreted as I intended.  If it seems like I am not giving you the information that you are asking for, then I must be misunderstanding the question or what you require as the answer; as far as I can see, everything asked has been answered.  I will try to answer your questions, below, but some of my answers are going to be repetitions/rephrasing of previous responses until I understand better what information is missing.

1.   Depending on what is being tested the 2851 is removed and replaced by the 4331.  Only the Client machine is connected to the 4331; it looks like the diagram that was provided.

1a.  An example of a difference being when I tested if there was anything upstream blocking the DNS resolution, after statically setting the Client's DNS to 8.8.8.8, I removed the 4331 from the diagram, inserted the 2851 and connected the client directly to it; I can make another image, when the resources are available to me, but it would look like the image I have already provided with the exception that the ISP terminates to GE 0/0 on the 2851 and the Client terminates to GE 0/1

1.   Unfortunately, I do not have the resources available to create a new diagram at this time.  I will attempt to do so as soon as possible.  I do not understand the second question in this has not already been answered in this response.  This I will not be able to provide until I am back onsite.  Yes, the client with DNS 8.8.8.8 can get DNS resolution when it is connected directly to port GE 0/0 on the router.  What evidence of this being tested are you looking for?  The results of an nslookup or from pinging a domain?  If those are what you are looking for, then those will also have to wait until I am back onsite unfortunately.

Taken out of the context of this entire thread, my previous response reads as if I am trying to do something new but this was simply a rephrasing of the problem I am experiencing:

Simply put

ISP -> Client assigned 4331's WAN IP and assigned the static DNS of 8.8.8.8 can get DNS resolution from 8.8.8.8 (verified by nslookup and ping)

ISP -> 2851 -> DHCP Client with static DNS of 8.8.8.8 can get DNS resolution from 8.8.8.8 (verified by nslookup and ping)

ISP -> 4331 -> DHCP Client with static DNS of 8.8.8.8 does not get DNS resolution from 8.8.8.8

I have been testing in this manner as it removes complexity from troubleshooting.

Please find the 2851's running config attached to this edited response.

@balaji.bandi  and @MHM Cisco World  the following screenshots are from the Client directly connected to the GE 0/1 interface of the 2851 with its production running config.  (ISP GW -> GE 0/0 of 2851 -> GE 0/1 of 2851 -> Client

Results of ipconfig /all with all fields supplied by DHCP from

Results of nslookup specifying the server as 8.8.8.8 (also shows dns timeout to internal DNS as client machine is connected to LAN interface GE 0/1

ipconfig /all after setting static dns, of 8.8.8.8 on client machine

Results of nslookup after setting static DNS of 8.8.8.8

Results of nslookup -debug with static dns to google.com (2 screenshots due to output)

Results of nslookup -debug with static dns to www.google.com (I lost the screenshot to the second page unfortunately)

Results of ping with static DNS of 8.8.8.8 to both google.com and www.google.com

[MHM Cisco World]

in OS do below and share result here 
nslookup -debug google.com

[T_K]