Martin Brown's questions

With Windows DHCP server I can have two servers serving a network's scope so that if one fails the other picks up the slack. With DHCPv4 there are two options for doing this, the first is to set up a fail over relationship, the other is to set the start and end of the scope on each of the servers so they don't overlap.

I'm trying to understand how this works with DHCPv6. When I set up a scope with v6 there is no way to set a start and end range and there is no way to set up a failover relationship. So my question is how is it that two servers prevent the situation where the same IP address is allocated to two different clients one by each of the two servers?

I have a program that is trying to register a URL with HTTP.SYS. It is giving the error "HTTP could not register URL http://+:1234/PathName/. Another application has already registered this URL with HTTP.SYS."

How can I find out what the other application is? Is there a command line I could run that would list all the registered URLs and the process ID that has them registered?

My company administrators have setup our machines to get proxy settings from a .pac file. The .pac file is complex and the proxy to use for a URL changes occasionally.

I often need to write powershell scripts that run tools that originate from linux e.g. git, pip, etc. These tools do not understand .pac files and don't use the normal windows network stack. I normally know which URLs these tools need to access and they tend to have a --proxy command line option that can be set.

My question is given a url is there any way to convert that into the correct proxy address that I can then pass to the tool I want to use? I can do this manually by reading the .pac file, but I'd like to script it.

I'm doing a course on AWS. What I'm trying to do is set up a VPC with two Linux servers. I've set up the VPC with two subnets. I have put one server in each. The idea is that one subnet is public the other is private.

I've created two Network ACLs and associated one with each subnet.

I can SSH from my machine to the server in the public subnet. When I try to SSH from that to the server in my private subnet I'm getting a connection timeout.

I'm not sure what rules I need to set in my two Network ACLs to get SSH working. Can anyone help? Given that I'm learning, I'd appreciate an explanation of why the rules should be, not just what the rules should be.

I have a VPC called MyVPC with CIDR 10.0.0.0/16
My first Subnet is called MyVPCSub1 CIDR 10.0.1.0/24
My second Subnet is called MyVPCSub2 CIDR 10.0.2.0/24
I have a route table called MyInternetRoute associated with MyVPCSub1 routes are :

|Dest        |Targ  |  
|10.0.0.0/16 |local |
|0.0.0.0/0   |igw   |

I have a route table called MyPrivate associated with MyVPCSub2 Routes are:

|Dest        |Targ  |
|10.0.0.0/16 |local |

I have a Network ACL called MyWeb associated with MyVPCSub1 with rules:

Inbound:

| #   | Type | Protocol | Ports | Source     | A/D
| 99  | HTTP | TCP      | 80    | {My IP}/32 | D
| 100 | HTTP | TCP      | 80    | 0.0.0.0/0  | A
| 200 | HTTPS| TCP      | 443   | 0.0.0.0/0  | A
| 300 | SSH  | TCP      | 22    | {My IP}/32 | A
| *   | ALL  | ALL      | ALL   | 0.0.0.0/0  | D

Outbound:

| #   | Type   | Protocol | Ports      | Source     | A/D
| 50  | ALL    | ALL      | ALL        | 0.0.0.0/0  | A
| 100 | HTTP   | TCP      | 80         | 0.0.0.0/0  | A
| 200 | HTTPS  | TCP      | 443        | 0.0.0.0/0  | A
| 300 | Custom | TCP      | 1024-65535 | 0.0.0.0/32 | A
| *   | ALL    | ALL      | ALL        | 0.0.0.0/0  | D

I have a Network ACL called MyPrivate associated with MyVPCSub2 with rules:

Inbound:

| #   | Type | Protocol | Ports | Source    | A/D
| 100 | ALL  | ALL      | ALL   | 0.0.0.0/0 | A
| *   | ALL  | ALL      | ALL   | 0.0.0.0/0 | D

Outbound:

| #   | Type | Protocol | Ports | Source    | A/D
| 100 | ALL  | ALL      | ALL   | 0.0.0.0/0 | A
| *   | ALL  | ALL      | ALL   | 0.0.0.0/0 | D

I have a custom server application that runs on Windows 2008 R2. It is a home grown Windows Service written in .Net supporting a number of custom terminals. I have a test machine that has a similar specification to the live server and I have a set of client simulators that I can use to produce a load that is a reasonable approximation of the real system. I need to be able to support 12,000 of these and at present the server is running out of memory (Paging is going through the roof).

My plan was to only start 100 of the simulators, measure memory usage, then start 100 more measure memory again and repeat until paging starts going up (In reality I will be taking more than three data points.) This should give me a figure for the amount of extra memory required for 100 simulators and enable me to project how much memory is required. I only need a rough idea +/-30Gb to avoid buying the full 2Tb ($150,000 worth) that the server will take. My question is whether this is a reasonable method to use and if so which Performance Counters would you monitor to give the amount of memory actually being used?

I am specifically talking about memory here as the difference between Working Set, Private Bytes, Committed, Shared, Virtual and all the other memory terms confuse me. I think I can manage to monitor CPU, IO and Networking by myself. The other thing I have noticed is that the .Net Cache adjusts its memory usage depending upon what is available which makes spotting a trend hard to see.

I want to install the new FTP 7.5 on a Windows 2008 server. Do I need to schedule this for a time when it is ok to Reboot the server?

I'm getting a 503 error when trying to access the localhost web site on my Windows 7 machine. When I look in the event log I'm getting a load of errors along the lies of:

Windows cannot copy file \\?\C:\Users\Default\{979ea7af-5041-4710-838e-f2a62d4ddad2}\symimv.cat to location \\?\C:\Users\TEMP.IIS APPPOOL.001\{979ea7af-5041-4710-838e-f2a62d4ddad2}\symimv.cat. This error may be caused by network problems or insufficient security rights. 

 DETAIL - Access is denied.

I have not touched the security permission on this DIR, has anyone any idea what might have caused this & how to resolve it? It seems to have started after doing a large number of windows updates last night.

One of my clients needs me to access their server using a Windows Remote Desktop connection. The trouble I have is that they are insisting on restricting access at the firewall to a single source IP address. My office ISP keep changing my IP address and it is becoming a nuisance getting the firewall updated each time.

I have a number of servers not doing much in a remote server farm. All of these do have a fixed IP address. Is there something I could install/setup on my servers that would allow me to have them reflect the RDP connection from my office PC to my Clients server?