Archive for January, 2012

DNS keeps track of Information in Zones. Essentially, a zone is a flat-file database for a particular domain, such as http://www.Google.com. The zone can contain different rexord types, all of which can be queried by clients:

> A : Which i a Host Address record – this resolves a single host name. suck as www, to an IP address.

> CNAME : or Alias – This resolves a name such as www to an actual host name, such as www1. think of it as a nickname for a computer -“www”, for example, is easier to remember and more standardized than a computer name like “w4salwin” which is what a Web Server’s real name might be.

> MX : or Mail Exchanger – This provides the name of the mail server for a Domain. Multiple MX records can be provided for fault tolerance or load balancing and a prioroty assigned to each. Clients, Such as sending mail servers, will attempt to contact the server in the MX record with the lowest-Numbered Priority.

> AAAA – This maps an IPv6 IP address to a host name.

> SRV: or Service – This provides the IP address of  one or more servers providing a particular service. AD uses SRV records to allow clients to locate Domain Controllers, among other things.

> SOA: or Start of Authority – This Special record indicates that the DNS Server hosting the zone is authoritative for the zone and is the primary source of name resolution for hosts within that domain.

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All active directory data base security related information store in SYSVOL folder and it’s only created on NTFS partition.

In Microsoft Windows, the System Volume (Sysvol) is a shared directory that stores the server copy of the domain’s public files that must be shared for common access and replication throughout a domain. The term SYSVOL refers to a set of files and folders that reside on the local hard disk of each domain controller in a domain and that are replicated by the File Replication service (FRS). Network clients access the contents of the SYSVOL tree by using the NETLOGON and SYSVOL shared folders.

The Sysvol folder on a Windows domain controller is used to replicate file-based data among domain controllers. Because junctions are used within the Sysvol folder structure, Windows NT file system (NTFS) version 5.0 is required on domain controllers throughout a Windows distributed file system (DFS) forest.

ReplMon can do the following:

  • See when a replication partner fails.
  • Display changes that have not yet replicated from a given replication partner.
  • Trigger the Knowledge Consistency Checker (KCC) to recalculate the replication topology.
  • View the history of successful and failed replication changes for troubleshooting purposes.
  • Find all direct and transitive replication partners on the network.
  • View the properties of directory replication partners.
  • Display the metadata of an Active Directory object’s attributes.
  • Poll replication partners and generate individual histories of successful and failed replication events.
  • Create your own applications or scripts written in Microsoft Visual Basic Scripting Edition (VBScript) to extract specific data from Active Directory.
  • View a snapshot of the performance counters on the computer, and the registry configuration of the server.
  • Generate status reports that include direct and transitive replication partners, and detail a record of changes.
  • Display replication topology.
  • Force replication.
  • Display a list of the trust relationships maintained by the domain controller being monitored.

Issue

  • The Service Console loses connectivity
  • Due to misconfiguration of service console, the network connection fails
  • An additional NIC is added to ESX host

Solution

To delete and recreate a virtual switch and Service Console from the command line:

 

  1. Run the following command to list the name of the vswif adapter:

    esxcfg-vswif -l

  2. Run the following command to delete the vswif adapter:

    esxcfg-vswif –del vswif0

  3. Run the following command to list the name of the vSwitch:

    esxcfg-vswitch -l

  4. Run the following command to delete the vSwitch:

    esxcfg-vswitch -d vSwitch0

  5. Run the following command to create the vSwitch:

    esxcfg-vswitch -a vSwitch0

  6. Run the following commands to create default port groups for vSwitch:

    esxcfg-vswitch -A “VM Network” vSwitch0
    esxcfg-vswitch -A “Service Console” vSwitch0

  7. Run the following command to create the vswif adapter:

    esxcfg-vswif –add –portgroup “Service Console” –ip=nnn.nnn.nnn.nnn –netmask=255.255.255.0 vswif0

  8. Run the following command to verify that the settings in the network file are correct:

    cat /etc/sysconfig/network

    NETWORKING=yes
    GATEWAYDEV=vswif0
    HOSTNAME=host.domain.com
    GATEWAY=nnn.nnn.nnn.nnn

  9. Run the following commands to list all of the network adapters and associate a vmnic which has a link status of up:

    esxcfg-nics -l
    esxcfg-vswitch -L vmnic1 vSwitch0

  10. Run the following command to verify that the vmnic is associated with the vSwitch:

    esxcfg-vswitch -l

  11. Ping an IP address to check for network connectivity. If the ping fails, remove the previous vmnic from the vSwitch and try another adapter that has a link status of up.

    esxcfg-vswitch -U vmnic1 vSwitch0
    esxcfg-vswitch -L vmnic2 vSwitch0

  12. Run the following command to change the vlan ID of a vSwitch:

    [root@server root]# esxcfg-vswitch -p “VM Network 1” -v 10 vSwitch0

  13. If you make any manual changes to /etc/sysconfig/network, run the following command to restart the network service:

    service network restart

  14. Done

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Here’s an excerpt:

The concert hall at the Syndey Opera House holds 2,700 people. This blog was viewed about 10,000 times in 2011. If it were a concert at Sydney Opera House, it would take about 4 sold-out performances for that many people to see it.

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