Brief Info about Checksum Offload

Brief Info about Checksum Offload
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When data comes in through a network, it's "checksummed," meaning the data is checked against a checksum (or validation code) in the headers in the packets it was delivered in. If the data and checksum don't match, the packet is determined to be bad and has to be retransmitted. 

To speed things up, some network cards can "offload" the checksumming, i.e., perform the checksumming on the network card itself, rather than leave the job to the CPU. This frees up the CPU to do that much more work on its own and on a server with extremely high network throughput that much CPU savings can add up. 

Windows 2003 Server and Windows 2008 server both have driver-level support for checksum offloading in many network cards (that is, when the card itself also supports it). However, sometimes this causes the network link on the computer in question to drop unexpectedly. And you may experience communication issues with DCs, GCs and clients.

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from : Disable checksum offloading to resolve network slowdown caused by Windows Firewall

Netstat

NETSTAT
=======
netstat -s   //shows packet information
netstat -arn // Persistant routes.
netstat
netstat -a
netstat -ano
netstat -abo
Route Print 

Belos is the Example to filter port 25 for TCP
netstat -an |file ":25" | file "TCP"

PORT

PORT
=====
Port 25; Simple Mail Transfer Protocol (SMTP) 465 (SSL)

DNS 53; TCP & UDP 

Port 80; Hypertext Transfer Protocol (HTTP) 

Port 88; Kerberos TCP & UDP 

Port 102; Message Transfer Agent (MTA) 

Port 110; Post Office Protocol v3 (POP3) (995, SSL)

Port 119; Network News Transfer Protocol (NNTP) 

Port 135; Exchange administration, RPC, client server communication   
RPC 135, 445 & all 1024+ port TCP 

Port 143, Internet Message Access Protocol version 4 (IMAP4) 

Port 389, Lightweight Directory Application Protocol (LDAP) TCP & UDP 

Port 443, HTTP using Secure Sockets Layer (SSL) 

port 465 (ssmtp), 

Port 563, NNTP using Secure Sockets Layer (SSL) 

Port 636, LDAP using Secure Sockets Layer (SSL) 

Port 691, Link State T

Port 993, IMAP4 using Secure Sockets Layer (SSL) 

Port 995, POP3 using Secure Sockets Layer (SSL) 

Port 3268 – Port 3269; Global catalog lookups 


On Exchange Server
=======================
CAS server to CAS server = TCP 80 and TCP 443
Hub server to Hub server = TCP_25
Hub server to Mailbox server = Ephermal port i.e Dynamic TCP port (1024-65535)
Mailbox server to Mailbox Server  = TCP 135, Dynamic TCP (1024-65535), UDP 3343, TCP 64327

NSlookup

Here are the few Examples for using NSLookup

nslookup -q=a "IP.domain.com"
Eg. nslookup -q=a "1.1.1.1.bl.spamcop.net"

In above examples, i am using bl.spamcop.net as an example and if you want to test with any other domain, use IP along with domain name.

set vc   // for tcp queries
server <10.2.124.133>

nslookup q=ptr
> type IP address to check whether IP address has reverse IP

in the same way you can change the query type to mx, a, txt,ns

q=mx //to query about MX record of the domain
q=a    //All
q=txt // TXT record
q=ns //name server 


Other tools can be used
--------------------------------
c:\> ARP -a 
c:\> Route Print

c:\> pathping -4 microsoft.com  (Microsoft.com domain is used as an Example)

Tools and parameter

NETMON PARAMETER
Ethereal  - smtp.rsp.parameter contains "Authentication unsuccessful"

NetMon ipv4.Address == 10.0.0.5 and ipv4.Address == 10.0.0.2

wireshark (ip.addr eq 10.0.0.5 and ip.addr eq 10.0.0.2)

experfwiz from
http://archive.msdn.microsoft.com/ExPerfwiz

Example
.\experfwiz.ps1 -server <Server FQDN> -interval 5 -filepath C:\Logs

Procdump
http://technet.microsoft.com/en-us/sysinternals/dd996900 

Syntax

=========

procdump.exe -ma -n <number of dumps> -s <number> -accepteula <servicename>.exe c:\dumps\<nameof the dump file>.dmp 

TOOLS
ExTrace.exe -v -c xx.etl >output.txt
aqadmcli.exe
delmsg flags=sender,sender=sender@domain_name.com
Ran aspnet_regiis -i from the \WINDOWS\Microsoft.NET\Framework\v2.0.50727 folder the issue was resolved.
Running ASPNET_REGIIS.EXE –i resolved the issue

Command to check SPN
----------------------------------------
ldifde -t 3268 -d "" -p subtree -r "(serviceprincipalname=*)" -f spn.txt

IIS BOX
========

Outbound : IIS box's IP should be added in the relay in the Exchange server box
Exchange server --> IIS box --> Internet
@IIS
Inbound : Remote domain

SBS SERVER 2003
====================================
How to troubleshoot the POP3 Connector in Windows Small Business Server 2003
http://support.microsoft.com/?scid=kb;en-us;885685&x=9&y=13

E-mail to external recipients with the same e-mail domain causes NDR messages when using the POP3 Connector
http://support.microsoft.com/kb/300681

Exchange Server Connector for POP3 Mailboxes deliver multiple copies of messages
http://support.microsoft.com/kb/264249

Enable logging from EMC (few eg.)
=====================
Get-EventlogLevel "MSExchange ADAccess" | Set-EventlogLevel -Level Lowest
Get-EventlogLevel "MSExchange Common" | Set-EventlogLevel -Level Lowest

Get-EventlogLevel "MSExchange ADAccess" | Set-EventlogLevel -Level Lowest


variable can be used as 
MSExchange Common\General                                                                                  Expert    
MSExchange Common\Configuration                                                                         Expert    
MSExchange Common\Logging                                                                                  Expert
MSExchange Configuration Cmdlet - Management Console\General                         Expert    
MSExchange Configuration Cmdlet - Management Console\RBAC                            Expert    
MSExchange ADAccess\General                                                                             Expert    
MSExchange ADAccess\Cache                                                                                Lowest    
MSExchange ADAccess\Topology                                                                           Expert    
MSExchange ADAccess\Configuration                                                                    Expert    
MSExchange ADAccess\LDAP                                                                                 Expert    
MSExchange ADAccess\Validation                                                                         Expert

MSExchange ADAccess\Site Update                                                                      Expert    

Image compression software
=======================
http://compressnow.com/        //it compresses the file to the % of the file

LDIFDE

LDIFDE example

c:\>ldifde -f delegates.txt -d "ou=users,dc=domain,dc=com" -l name,publicDelegates,publicDelegatesBL -r "(|(publicDelegates=*)(publicDelegatesBL=*))"

Outlook "Test E-mail Autoconfiguration" and "Connection Status"

"Test E-mail Autoconfiguration" for outlook


1. Hold Control Key and Right click outlook icon bottom right of the task bar. It might be possible that Outlook Icon is hidden in Notification bar. If it is so Click and drag icon into task bar.

2. From Popup-menu Test E-mail Autoconfiguration.

3. Select only “Use AutoDiscover” and then click Test button


Similarly you can check the "Connection Status" to check which GC/CAS/FE server Outlook is connected to.

Here is the Image of both of the Options